tag (“featured” in this case) when the recipe is a featured recipe. That adds some special highlighting to make the title stand out even more. The final thing to note is the ng-submit directive on the form. The directive states that the edit() function on the scope is called in case the form is submitted. The form submission happens when any button without an explicit function attached (in this case, the Edit button) is clicked. Again, AngularJS is smart enough to figure out the scope that is being referred to (from the module, the route, and the controller) and call the right method at the right time. Now we can move on to our final template (and possibly the most complicated one yet), the recipe form template.

Edit Recipe

tag is scoped to the Ingredients Controller. But what about the actual controller of this template, the Edit Control‐ ler? As it turns out, the Ingredients Controller is created as a child controller of the Edit Controller, thereby inheriting the scope of Edit Controller. That is why it has access to the recipe object from the Edit Controller. In addition, it adds the addIngredient() method, which is used by the highlighted ng-click, which is accessible only within the scope of the
tag. Why would you want to do this? This is the best way to separate your concerns. Why should the Edit Controller have an addIngredients() method, when 99% of the template doesn’t care about it? Child and nested controllers are awesome for such precise, contained tasks, and allow you to separate your business logic into more manage‐ able chunks. • The other directive that we want to cover in some depth here is the form validation controls. It is easy enough in the AngularJS world to set a particular form field “as required.” Simply add the required tag to the input (as is the case in the preceding code). But now what do you do with it? For that, we jump down to the Save button. Notice the ng-disabled directive on it, which says recipeForm.$invalid. The recipeForm is the name of the form which we have declared. AngularJS adds some special variables to it ($valid and $invalid being just two) that allow you to control the form elements. AngularJS 94 | Chapter 4: Analyzing an AngularJS App looks at all the required elements and updates these special variables accordingly. So if our Recipe Title is empty, recipeForm.$invalid gets set to true (and $val id to false), and our Save button is instantly disabled. We can also set the max and min length of an input, as well as a Regex pattern against which an input field will be validated. Furthermore, there are advanced usages that can be applied to show certain error messages only when specific conditions are met. Let us diverge for a bit with a small example:
User name: Too Short!
In the preceding example, we add a requirement that the username be at least three characters (through the use of the ng-minlength directive). Now, the form gets popu‐ lated with each named input in its scope—we have only userName in this example— each of which will have an $error object (which will further include what kind of error it has or doesn’t have: required, minlength, maxlength, or pattern) and a $valid tag to signal whether the input itself is valid or not. We can use this to selectively show error messages to the user, depending on the type of input error he is making, as we do in the previous example. Jumping back to our original template—Recipe form template—there is another nice usage of the ng-show highlighted within the ingredients repeater scope. The Add In‐ gredient button is shown only beside the last ingredient. This is accomplished by calling an ng-show and using the special $last variable that is accessible inside a repeater element scope. Finally, we have the last ng-click, which is attached to the second button, used for deleting the recipe. Notice how the button only shows if the recipe is not saved yet. While usually it would make more sense to write ng-hide="recipe.id", sometimes it makes more semantic sense to say ng-show="!recipe.id". That is, show if the recipe doesn’t have an id, rather than hide if the recipe has an id. The Tests We have been holding off on showing you the tests that go along with the controller, but you knew they were coming, didn’t you? In this section, we’ll go over what kinds of tests you would write for which parts of the code, and how you would actually write them. The Tests | 95 Unit Tests The first and most important kind of test is the unit test. This tests that the controllers (and directives, and services) that you have developed are correctly structured and written, and that they do what you would expect them to. Before we dive into the individual unit tests, let us take a look at the test harness that surrounds all of our controller unit tests: describe('Controllers', function() { var $scope, ctrl; //you need to indicate your module in a test beforeEach(module('guthub')); beforeEach(function() { this.addMatchers({ toEqualData: function(expected) { return angular.equals(this.actual, expected); } }); }); describe('ListCtrl', function() {....}); // Other controller describes here as well }); The harness (we are still using Jasmine to write these tests in a behavioral manner) does a few things: 1. Creates a globally (at least for the purpose of this test spec) accessible scope and controller, so we don’t worry about creating a new variable for each controller. 2. Initializes the module that our app uses (GutHub in this case). 3. Adds a special matcher that we call equalData. This basically allows us to perform assertions on resource objects (like recipes) that are returned through the $re source service or RESTful calls. Remember to add the special matcher called equalData any time we want to do assertions on ngResource returned objects. This is because ngResource returned objects have additional methods on them that will fail normal expect equal calls. With that harness in place, let’s take a look at the unit tests for the List Controller: describe('ListCtrl', function() { var mockBackend, recipe; // _$httpBackend_ is the same as $httpBackend. Only written this way to 96 | Chapter 4: Analyzing an AngularJS App // differentiate between injected variables and local variables beforeEach(inject(function($rootScope, $controller, _$httpBackend_, Recipe) { recipe = Recipe; mockBackend = _$httpBackend_; $scope = $rootScope.$new(); ctrl = $controller('ListCtrl', { $scope: $scope, recipes: [1, 2, 3] }); })); it('should have list of recipes', function() { expect($scope.recipes).toEqual([1, 2, 3]); }); }); Remember that the List Controller is one of the simplest controllers we have. The con‐ structor of the controller just takes in a list of recipes and saves it to the scope. You could write a test for it, but it seems kind of silly (we still did it, because tests are awesome!). Instead, the more interesting aspect is the MultiRecipeLoader service. This is respon‐ sible for fetching the list of recipes from the server and passing it in as an argument (when hooked up correctly via the $route service): describe('MultiRecipeLoader', function() { var mockBackend, recipe, loader; // _$httpBackend_ is the same as $httpBackend. Only written this way to // differentiate between injected variables and local variables. beforeEach(inject(function(_$httpBackend_, Recipe, MultiRecipeLoader) { recipe = Recipe; mockBackend = _$httpBackend_; loader = MultiRecipeLoader; })); it('should load list of recipes', function() { mockBackend.expectGET('/recipes').respond([{id: 1}, {id: 2}]); var recipes; var promise = loader(); promise.then(function(rec) { recipes = rec; }); expect(recipes).toBeUndefined(); mockBackend.flush(); expect(recipes).toEqualData([{id: 1}, {id: 2}]); }); }); // Other controller describes here as well The Tests | 97 We test the MultiRecipeLoader by hooking up a mock HttpBackend in our test. This comes from the angular-mocks.js file that is included when these tests are run. Just injecting it into your beforeEach method is enough for you to start setting expectations on it. In our second, more meaningful test, we set an expectation for a server GET call to recipes, which will return a simple array of objects. We then use our new custom matcher to ensure that this is exactly what was returned. Note the call to flush() on the mock backend, which tells the mock backend to now return response from the server. You can use this mechanism to test control flow and see how your application handles before and after the server returns a response. We will skip View Controller, as it is almost exactly like the List Controller except for the addition of an edit() method on the scope. This is pretty simple to test, as you can inject the $location into your test and check its value. Let us now jump to the Edit Controller, which has two points of interest that we should be unit testing. The resolve function is similar to the one we saw before, and can be tested the same way. Instead, we now want to see how we can test the save() and the remove() methods. Let’s take a look at the tests for those (assuming our harnesses from the previous example): describe('EditController', function() { var mockBackend, location; beforeEach(inject(function($rootScope, $controller, _$httpBackend_, $location, Recipe) { mockBackend = _$httpBackend_; location = $location; $scope = $rootScope.$new(); ctrl = $controller('EditCtrl', { $scope: $scope, $location: $location, recipe: new Recipe({id: 1, title: 'Recipe'}) }); })); it('should save the recipe', function() { mockBackend.expectPOST('/recipes/1', {id: 1, title: 'Recipe'}).respond({id: 2}); // Set it to something else to ensure it is changed during the test location.path('test'); $scope.save(); expect(location.path()).toEqual('/test'); mockBackend.flush(); 98 | Chapter 4: Analyzing an AngularJS App expect(location.path()).toEqual('/view/2'); }); it('should remove the recipe', function() { expect($scope.recipe).toBeTruthy(); location.path('test'); $scope.remove(); expect($scope.recipe).toBeUndefined(); expect(location.path()).toEqual('/'); }); }); In the first test, we test the save() function. In particular, we ensure that saving first makes a POST request to the server with our object, and then, once the server responds, the location is changed to the newly persisted object’s view recipe page. The second test is even simpler. We simply check to ensure that calling remove() on the scope removes the current recipe, then redirects the user to the main landing page. This can be easily done by injecting the $location service into our test, and working with it. The rest of the unit tests for the controllers follow very similar patterns, so we can skip over them. At their base, such unit tests rely on a few things: • Ensuring that the controller (or more likely, the scope) reaches the correct state at the end of the initialization • Confirming that the correct server calls are made, and that the right state is achieved by the scope during the server call and after it is completed (by using our mocked out backend in the unit tests) • Leveraging the AngularJS dependency injection framework to get a handle on the elements and objects that the controller works with to ensure that the controller is getting set to the correct state Scenario Tests Once we are happy with our unit tests, we might be tempted to just lean back, smoke a cigar, and call it a day. But the work of an AngularJS developer isn’t done until he has run his scenario tests. While unit tests assure us that every small piece of JS code is working as intended, we also want to ensure that the template loads, that it is hooked up correctly to the controllers, and that clicking around in the template does the right thing. The Tests | 99 This is exactly what a scenario test in AngularJS does for you. It allows you to: • Load your application • Browse to a certain page • Click around and enter text willy-nilly • Ensure that the right things happen So how would a scenario test for our “list of recipes” page work? Well, first of all, before we get started on the actual test, we need to do some groundwork. For the scenario test to work, we will need a working web server that is ready to accept requests from the GutHub application, and will allow storing and getting a list of recipes from it. Feel free to change the code to use an in-memory list of recipes (removing the recipe $resource and changing it to just a JSON object dump), or to reuse and modify the web server we showed you in the previous chapter, or to use Yeoman! Once we have a server up and running, and serving our application, we can then write and run the following test: describe('GutHub App', function() { it('should show a list of recipes', function() { browser().navigateTo('/index.html'); // Our Default GutHub recipes list has two recipes expect(repeater('.recipes li').count()).toEqual(2); }); }); 100 | Chapter 4: Analyzing an AngularJS App CHAPTER 5 Communicating with Servers Up to this point, we have mostly seen how your AngularJS application should be laid out, how the different AngularJS pieces fit together and work, and a bit on how tem‐ plating in AngularJS works. Together, this allows you to build some sleek, sexy apps, but they are restricted mostly to the client side. We saw a little bit of the server-side communication with the $http service back in Chapter 2, but in this chapter, we’ll dig a little bit deeper into how you would use it in a real-world application. In this chapter, we will talk about how AngularJS allows you to communicate with your server, both at the lowest levels of abstraction and with the nice wrappers that it provides. Furthermore, we will go into how AngularJS can help you speed up your application with its built-in caching mechanism. If you want to develop a realtime application with AngularJS using SocketIO, there is an example in Chapter 8 of a possible way to wrap SocketIO as a directive and use it, so we won’t cover that here. Communicating Over $http The traditional way of making a request to the server from AJAX applications (using XMLHttpRequests) involves getting a handle on the XMLHttpRequest object, making the request, reading the response, checking the error codes, and finally processing the server response. It goes something like this: var xmlhttp = new XMLHttpRequest(); xmlhttp.onreadystatechange = function() { if (xmlhttp.readystate == 4 && xmlhttp.status == 200) { var response = xmlhttp.responseText; } else if (xmlhttp.status == 400) { // or really anything in the 4 series // Handle error gracefully } }; 101 // Setup connection xmlhttp.open(“GET”, “http://myserver/api”, true); // Make the request xmlhttp.send(); This is a lot of work for such a simple, common, and often repeated task. If you want to do it repeatedly, you will likely end up creating wrappers or using a library. The AngularJS XHR API follows what is commonly known as the Promise interface. As XHRs are asynchronous method calls, the response from the server will come back at an unknown future date and time (hopefully almost immediately!). The Promise interface guarantees how such responses will be dealt with, and allows consumers of the Promise to use them in a predictable manner. Suppose we wanted to fetch a user’s information from our server. If the API is available at /api/user, and accepts the id as a URL parameter, then our XHR request using An‐ gular’s core $http service would look something like the following: $http.get('api/user', {params: {id: '5'} }).success(function(data, status, headers, config) { // Do something successful. }).error(function(data, status, headers, config) { // Handle the error }); If you are from the jQuery world, you should notice how similarly AngularJS and jQuery interact with asynchronous requests. The $http.get method we used in the preceding example is just one of the many con‐ venience methods that the core $http AngularJS service provides. Similarly, if you wanted to make a POST request using AngularJS with the same URL parameters and some POST data, you would do so as follows: var postData = {text: 'long blob of text'}; // The next line gets appended to the URL as params // so it would become a post request to /api/user?id=5 var config = {params: {id: '5'}}; $http.post('api/user', postData, config ).success(function(data, status, headers, config) { // Do something successful }).error(function(data, status, headers, config) { // Handle the error }); 102 | Chapter 5: Communicating with Servers Similar convenience methods are provided for most of the common request types, in‐ cluding: • GET • HEAD • POST • DELETE • PUT • JSONP Configuring Your Request Further At times, the standard request options provided out of the box are not enough. This could be because you want to: • Add some authorization headers for your request • Change how caching is handled for the request • Transform the request going out, or the response coming in, in certain set ways In such cases, you can configure your request further through the optional configuration object passed to the requests. In the prior example, we used the config object to specify optional URL parameters. But even the GET and POST methods we showed there are convenience methods. The barebones method call would look something like: $http(config) What follows is a basic pseudo-code template for calling this method: $http({ method: string, url: string, params: object, data: string or object, headers: object, transformRequest: function transform(data, headersGetter) or an array of functions, transformResponse: function transform(data, headersGetter) or an array of functions, cache: boolean or Cache object, timeout: number, withCredentials: boolean }); Communicating Over $http | 103 The GET, POST, and other convenience methods set the method, so you don’t need to. The config object gets passed in as the last argument to $http.get, $http.post, so you can still use it while using any of the convenience methods. You can change the request being made by passing the config object set with the fol‐ lowing keys: method A string representing the HTTP request type, like GET, or POST url A URL string representing the absolute or relative URL of the resource being re‐ quested params An object (a map to be precise) of string-to strings, representing keys and values that will be translated to URL parameters. For example: [{key1: 'value1', key2: 'value2'}] would be converted to: ?key1=value1&key2=value2 after the URL. If we use an object, instead of a string or a number, for the value, the object will be converted to a JSON string. data A string or an object that will be sent as the request message data timeout The time in milliseconds to wait before the request is treated as timed out There are a few more options that can be configured, which we will explore in more depth in the following sections. Setting HTTP Headers AngularJS has default headers which it applies to all outgoing requests, which include the following: 1. Accept: application/json, text/plain, / 2. X-Requested-With: XMLHttpRequest If there are any special headers you want to set, there are two ways of doing so. 104 | Chapter 5: Communicating with Servers The first way, if you think you are going to apply these headers to each and every out‐ going request, is to make your special header part of the default headers for AngularJS. These are set in the $httpProvider.defaults.headers configuration object. This step is usually done in the config part of setting up your app. So if you wanted to enable “DO NOT TRACK” for all your GET requests, while removing the Requested-With header for all your requests, you could simply do the following: angular.module('MyApp',[]). config(function($httpProvider) { // Remove the default AngularJS X-Request-With header delete $httpProvider.default.headers.common['X-Requested-With']; // Set DO NOT TRACK for all Get requests $httpProvider.default.headers.get['DNT'] = '1'; }); If you want to set the headers for only certain requests, but not as a default, then you can pass the header in as part of the config object to $http service. The same custom header can be passed to a GET request as part of the second parameter, which also takes your URL parameters: $http.get('api/user', { // Set the Authorization header. In an actual app, you would get the auth // token from a service headers: {'Authorization': 'Basic Qzsda231231'}, params: {id: 5} }).success(function() { // Handle success }); For a full-fledged example of how to handle authorization within your application, turn to the Cheatsheets example in Chapter 8. Caching Responses AngularJS provides a simple caching system for your HTTP GET requests out of the box. It comes disabled for all requests by default, but to enable caching for your requests, all you need to do is: $http.get('http://server/myapi', { cache: true }).success(function() { // Handle success }); This enables the cache, and AngularJS stores the response from the server. The next time a request is made for the same URL, AngularJS returns the response from the cache. The cache is also smart, so even if you make multiple simultaneous requests for the same URL, only one request is made to the server and the response is used to fulfill all the requests. However, this might be jarring from a usability standpoint, as a user would first see the old results, then the new results would suddenly show up. For example, a user might be about to click on an item, and it might change under him. Communicating Over $http | 105 Note that the response (even if it is being served from the cache), is still asynchronous in nature. In other words, expect your code to behave as it did when it first made the request. Transformations on Requests and Responses AngularJS applies some basic transformations on all requests and responses made through its $http service. These include: Request transformations If the data property of the requested config object contains an object, serialize it into JSON format. Response transformations If an XSRF prefix is detected, strip it. If a JSON response is detected, deserialize it using a JSON parser. If you don’t want some of the transformations, or want to add your own, then you can pass in your functions as part of the config. These functions get the HTTP request/ response body, as well as the headers, and respond with the serialized, modified version. Set these config functions using the transformRequest and transformResponse keys, which are configured using the $httpProvider service in the config function of the module. When would we use these? Let us assume that we have a server which is more attuned to the jQuery way of doing things. It would expect our POST data to come in the form key1=val1&key2=val2 (that is, a string), instead of the JSON form of {key1: val1, key2: val2}. While we could make this change at every request, or add a transform Request call individually, for the purpose of this example, we are going to add a general transformRequest, so that for all outgoing calls, this transformation from JSON form to a string happens. Here’s how we would do this: var module = angular.module('myApp'); module.config(function ($httpProvider) { $httpProvider.defaults.transformRequest = function(data) { // We are using jQuery’s param method to convert our // JSON data into the string form return $.param(data); }; }); 106 | Chapter 5: Communicating with Servers Unit Testing So far, we have seen how you can use the $http service and configure it in all the possible ways you might want to. But what about writing some unit tests to ensure that it actually works? As we have mentioned repeatedly, AngularJS was designed with testing in mind, so of course it has a mocked backend that allows you to test whether the right requests are being made, and even to control how and when the response is handled, right from your unit test. Let us explore how you would unit test a controller that makes a request to your server, fetches some data from it, and sets it on the scope to be displayed by the view in some particular format. Our NamesListCtrl is a very simple controller that has one purpose for its existence: to hit our names API, then store all the names on the scope. function NamesListCtrl($scope, $http) { $http.get('http://server/names', {params: {filter: ‘none’}}). success(function(data) { $scope.names = data; }); } How would we unit test this? In our unit test, we would like to ensure that: • NamesListCtrl can find all its dependencies (and get them injected correctly). • The controller makes the request to fetch the names from the server as soon as it loads. • The controller correctly saves the response to the names variable on the scope. While we could construct a controller in our test, and inject a scope and fake HTTP service into it, let us instead construct the test the same way AngularJS would in its production code. This is the recommended way, despite it looking a bit more compli‐ cated. Let’s take a look: describe('NamesListCtrl', function(){ var scope, ctrl, mockBackend; // AngularJS is responsible for injecting these in tests beforeEach(inject(function(_$httpBackend_, $rootScope, $controller) { // This is a fake backend, so that you can control the requests // and responses from the server mockBackend = _$httpBackend_; // We set an expectation before creating our controller, Unit Testing | 107 // because this call will get triggered when the controller is created mockBackend.expectGET('http://server/names?filter=none'). respond(['Brad', 'Shyam']); scope = $rootScope.$new(); // Create a controller the same way AngularJS would in production ctrl = $controller(PhoneListCtrl, {$scope: scope}); })); it('should fetch names from server on load', function() { // Initially, the request has not returned a response expect(scope.names).toBeUndefined(); // Tell the fake backend to return responses to all current requests // that are in flight. mockBackend.flush(); // Now names should be set on the scope expect(scope.names).toEqual(['Brad', 'Shyam’]); }); }); Working with RESTful Resources The $http service provides a very low-level implementation that allows you to make XHR requests, but still gives you a lot of control and flexibility. But in a majority of cases, we deal with objects and object models that are encapsulated with certain properties and methods, like a person object (with his details), or a credit card object. In such cases, wouldn’t it be nice if we could create a JS object that understands and represents this object model? If we could just edit the properties of this object, say save or update, and the state would get persisted on the server? The $resource allows for this very capability. AngularJS resources allow us to define object models, and in a descriptive manner, to specify: • The server-side URL for the resource • The types of parameters that are commonly seen for such requests • Some additional methods (you automatically get get, save, query, remove, and delete for free) that encapsulate specific functionality and business logic for the object model (like charge() for a credit card) • The expected types of responses (an array or an object) • The headers 108 | Chapter 5: Communicating with Servers When Can You Use Angular Resources? You should only use Angular resources if your server side behaves in a RESTful manner. For the case of a credit card, which we will be using as an example in this part of the chapter that entails: 1. A GET request to /user/123/card returns a list of credit cards for User 123. 2. A GET request to /user/123/card/15 returns the credit card with ID 15 for User 123. 3. A POST request to /user/123/card with credit card info in the POST data creates a new credit card for User 123. 4. A POST request to /user/123/card/15 with credit card info in the POST data updates the credit card for User 123 with ID 15. 5. A DELETE request to /user/123/card/15 deletes the credit card with ID 15 for User 123. In addition to providing objects that allow you to query the server as per your require‐ ments, $resource also allows you to work with the returned objects as if they were persisted data models, make changes, and ask them to be persisted. The ngResource is a separate, optional module. To use it, you need to: • Include the angular-resource.js in your script files that are sourced. • Include ngResource in your module dependency declaration (such as, angular.mod ule(‘myModule’, [‘ngResource’])). • Use inject $resource where needed. Before we look at how we would use the ngResource method of creating a resource, let us take a look at what it would take to create something similar using the base $http service. For our credit card resource, we want to be able to get, query, and save credit cards, in addition to being able to “charge” a credit card. Here’s one possible implementation: myAppModule.factory('CreditCard', ['$http', function($http) { var baseUrl = '/user/123/card'; return { get: function(cardId) { return $http.get(baseUrl + '/' + cardId); }, save: function(card) { var url = card.id ? baseUrl + '/' + card.id : baseUrl; return $http.post(url, card); Working with RESTful Resources | 109 }, query: function() { return $http.get(baseUrl); }, charge: function(card) { return $http.post(baseUrl + '/' + card.id, card, {params: {charge: true}}); } }; }]); Instead, you could easily create an Angular service that reflects your resource through‐ out the app as follows: myAppModule.factory('CreditCard', ['$resource', function($resource) { return $resource('/user/:userId/card/:cardId', {userId: 123, cardId: '@id'}, {charge: {method:'POST', params:{charge:true}, isArray:false}); }]); Now, whenever we ask for a CreditCard from the AngularJS injector, we get an Angular resource, which by default gives us a few methods to start off with. Table 5-1 lists what the methods are, and how they behave, so you know how the server should be config‐ ured. Table 5-1. A credit card resource Resource Function Method URL Expected Return CreditCard.get({id: 11}) GET /user/123/card/11 Single JSON CreditCard.save({}, ccard) POST /user/123/card with post data “ccard” Single JSON CreditCard.save({id: 11}, ccard) POST /user/123/card/11 with post data “ccard” Single JSON CreditCard.query() GET /user/123/card JSON Array CreditCard.remove({id: 11}) DELETE /user/123/card/11 Single JSON CreditCard.delete({id: 11}) DELETE /user/123/card/11 Single JSON Let’s take the example of a credit card, which should make things clearer. // Let us assume that the CreditCard service is injected here // We can retrieve a collection from the server which makes the request // GET: /user/123/card var cards = CreditCard.query(); // We can get a single card, and work with it from the callback as well CreditCard.get({cardId: 456}, function(card) { // each item is an instance of CreditCard expect(card instanceof CreditCard).toEqual(true); card.name = "J. Smith"; // non-GET methods are mapped onto the instances card.$save(); 110 | Chapter 5: Communicating with Servers // our custom method is mapped as well. card.$charge({amount:9.99}); // Makes a POST: /user/123/card/456?amount=9.99&charge=true // with data {id:456, number:'1234', name:'J. Smith'} }); A lot of things happen in the preceding example, so we’ll call out the important parts one by one: The Declaration Declaring your own $resource is as simple as calling the injected $resource function (you know how to inject things by now, right?) with the right parameters. The $resource function takes one required argument—the URL at which the resource is available—and two optional arguments: default parameters and additional actions you want to configure on the resource. Notice that the URL parameter is parametrized (the : denotes a parameter. The :user Id states that the userId parameter will replace the text there, and the :cardId will be replaced by the value of the cardId parameter). If the parameter is not passed, then it will be replaced by an empty string. The second parameter takes care of the default parameters to be passed along with each request. In this case, we pass in the userId as a constant 123. The cardId parameter is more interesting. We say cardId is "@id.” This denotes that if I am using a returned object from the server, and I call any method on it (such as $save), then the cardId field is to be picked from the id property on the object. The third argument is other methods we would like to expose on our custom resource. We’ll cover this in depth in the following section. Custom Methods The third argument to the $resource call is optional additional methods you want to expose on your resource. In this case, we specify a method charge. This can be configured by passing in an object, with the key being the method name to be exposed. The configuration needs to specify the method type of the request (GET, POST, and so on), the parameters that need to be passed as part of that request (charge=true in this case), and if the returned result is an array or not (not, in this case). Once that is done, you are free to start calling Credit Card.charge() whenever you want (as long as the user has charged in real life, of course!). Working with RESTful Resources | 111 No Callbacks! (Unless You Really Want Them) The third thing to notice is the return type of the resource call. Take a look at the CreditCard.query() call again. You will see that instead of assigning the cards in a callback, we are directly assigning them to the card’s variable. With an asynchronous server request, will that code even work? You would be correct to worry about whether the code will work, but the code is actually correct and will work. What’s happening here is that AngularJS assigned a reference (an object or an array, depending on the expected return type), which will get populated at some point in the future when the server requests returns. In the meantime, the object will remain empty. Since the most common flow with AngularJS apps is to fetch data from the server, assign it to a variable, and display it in the template, this shortcut is nice. In your controller code, all you have to do is make the server-side call, assign the return value to the right scope variable, and let the template worry about rendering it when it returns. This approach will not work for you if you have some business logic you want executed on the return value. In such a case, you will have to depend on the callback, which is used in the CreditCard.get() call. Simplified Server-Side Operations Regardless of whether you use the shortcut return type or the callback, there are some other points you should note about the returned object. The return value is not a plain old JS object, but in fact a “resource” type object. This means that in addition to the value returned by the server, it has some additional be‐ havior attached to it (the $save() and $charge() in this case). This allows you to per‐ form server-side operations with ease, for example by fetching data, making some changes, and persisting the changes to the server (the most common behavior in any CRUD app). Unit Test the ngResource The ngResource is an encapsulation, and uses the $http core AngularJS at its base. Thus, you already know how to unit test it. Nothing really changes from the unit testing example we saw for $http. You only need to know the final request that is expected to be made by the resource, tell the fake $http service about it, and everything else should be exactly the same. Let’s take a look at a test for our preceding code: describe('Credit Card Resource', function(){ var scope, ctrl, mockBackend; beforeEach(inject(function(_$httpBackend_, $rootScope, $controller) { mockBackend = _$httpBackend_; 112 | Chapter 5: Communicating with Servers scope = $rootScope.$new(); // Assume that CreditCard resource is used by the controller ctrl = $controller(CreditCardCtrl, {$scope: scope}); })); it('should fetched list of credit cards', function() { // Set expectation for CreditCard.query() call mockBackend.expectGET('/user/123/card'). respond([{id: '234', number: '11112222'}]); ctrl.fetchAllCards(); // Initially, the request has not returned a response expect(scope.cards).toBeUndefined(); // Tell the fake backend to return responses to all current requests // that are in flight. mockBackend.flush(); // Now cards should be set on the scope expect(scope.cards).toEqualData([{id: '234', number: '11112222'}]); }); }); This test should look extremely similar to the simple $http unit test, except for one minor difference. Notice how in our expectation, instead of using the simple “equals” method, we are using a special toEqualData call. This expectation is smart enough to ignore the additional methods that the ngResource adds to an object. The $q and the Promise So far, we have seen how AngularJS implements its asynchronous, deferred API. The Promise proposal is the basis for how AngularJS structures its API. At its base, the Promise proposal dictates the following for asynchronous requests: • Async requests return a promise instead of a return value. • The Promise has a then function, which takes two arguments, a function to handle the “resolved” or “success” event, and a function to handle the “rejected” or the “failure” event. These functions are called with the result, or the reason for the rejection. • It is guaranteed that one of the two callbacks will be called, as soon as the result is available. While most deferred/Q implementations follow this kind of approach, AngularJS’ im‐ plementation is special for the following reasons: The $q and the Promise | 113 • The $q is AngularJS aware, and thus is integrated with the scope model. This allows for faster propagation of resolution and less flicker/updates in the UI • AngularJS templates also recognize the $q promises, and thus they can be treated as the resultant value themselves instead of a promise, which will be notified of the result. • A smaller footprint, as AngularJS implements only the basic, most important func‐ tionality needed for common async tasks. You might ask the question: why would you want to do something so crazy? Let’s take a look at a standard problem you might run into with asynchronous functions: fetchUser(function(user) { fetchUserPermissions(user, function(permissions) { fetchUserListData(user, permissions, function(list) { // Do something with the list of data that you want to display }); }); }); This is the dreaded pyramid of doom that people complain about when working with JavaScript. The asynchronous nature of returns competes with the synchronous needs of the program, leading to multiple nested functions, making it that much harder to keep track of the current context. In addition, there is also the matter of error handling. What is the best way to handle errors? Do you do it in each step? That also gets messy. To fix this, the Promise proposal offers the concept of then, which takes the functions to execute in case of a success, on one hand, and error on the other, each of which can also be chained. So the preceding example, with the Promise API (AngularJS’ imple‐ mentation, at least), could be flattened to: var deferred = $q.defer(); var fetchUser = function() { // After async calls, call deferred.resolve with the response value deferred.resolve(user); // In case of error, call deferred.reject(‘Reason for failure’); } // Similarly, fetchUserPermissions and fetchUserListData are handled deferred.promise.then(fetchUser) .then(fetchUserPermissions) .then(fetchUserListData) .then(function(list) { // Do something with the list of data }, function(errorReason) { 114 | Chapter 5: Communicating with Servers // Handle error in any of the steps here in a single stop }); The whole pyramid is flattened nicely, and provides scope for chaining, as well as a single point of error handling. You can use the same code in your application for han‐ dling asynchronous calls by including the $q AngularJS service. This mechanism also allows us to do something very cool: response interception! Response Interception We have covered making calls to the server, handling responses, wrapping the responses nicely in abstractions, and dealing with asynchronous calls. But in any real world ap‐ plication, you would end up having to do some common operations for each server call you made, tasks such as error handling, authentication, and other security considera‐ tions like pruning the data. With a solid understanding of the $q API, we can now set about doing all of the above using Response Interceptors. Response Interceptors allow you (as the name would suggest) to intercept responses before they make it to the application, and apply your transformations, error handling, and everything else, including the kitchen sink. Let us take an example which intercepts the responses and does some minor data trans‐ formation. // register the interceptor as a service myModule.factory('myInterceptor', function($q, notifyService, errorLog) { return function(promise) { return promise.then(function(response) { // Do nothing return response; }, function(response) { // My notify service updates the UI with the error message notifyService(response); // Also log it in the console for debug purposes errorLog(response); return $q.reject(response); }); } }); // Ensure that the interceptor we created is part of the interceptor chain $httpProvider.responseInterceptors.push('myInterceptor'); Security Considerations Now, when working with web applications, security is a huge concern and should be kept at the top of one’s mind. AngularJS does provide some assistance when it comes to two common attack vectors, which we will cover in the following sections. Response Interception | 115 JSON Vulnerability There is a very subtle JSON vulnerability which is exposed when a GET request is made to retrieve JSON information as an array (especially if the information is sensitive and requires login credentials or authentication to access). The vulnerability involves a malicious site which uses a The id attribute here is important, as this is the URL key that Angular uses to store the template. You’ll use this id later in your directive’s templateUrl to specify which tem‐ plate to insert. This version will load just fine without a server, as no XMLHttpRequest is necessary to fetch the content. Finally, you could load the templates yourself over $http or another mechanism and then set them directly in the object Angular uses called the $templateCache. We want this template available in the cache before the directives run, so we’ll call it via a run function on our module. var appModule = angular.module('app', []); appModule.run(function($templateCache) { $templateCache.put('helloTemplateCached.html', '
Hi there
'); }); appModule.directive('hello', function() { return { restrict: 'E', templateUrl: 'helloTemplateCached.html', replace: true }; }); You would likely want to do this in production only as a technique to reduce the number of GET requests required. You’d run a script to concatenate all the templates into a single file, and load it in a new module that you then reference from your main application module. API Overview | 125 Transclusion In addition to replacing or appending the content, you can also move the original con‐ tent within the new template through the transclude property. When set to true, the directive will delete the original content, but make it available for reinsertion within your template through a directive called ng-transclude. We could change our example to use transclusion: appModule.directive('hello', function() { return { template: '
Hi there
', transclude: true }; }); applying it as:
Bob
We would see: “Hi there Bob.” Compile and Link Functions While inserting templates is useful, the really interesting work of any directive happens in its compile or its link function. The compile and link functions are named after the two phases Angular uses to create the live view for your application. Let’s take a high-level view of Angular’s initialization process, in order: Script loads Angular loads and looks for the ng-app directive to find the application boundaries. Compile phase In this phase, Angular walks the DOM to identify all the registered directives in the template. For each directive, it then transforms the DOM based on the directive’s rules (template, replace, transclude, and so on), and calls the compile function if it exists. The result is a compiled template function, which will invoke the link functions collected from all of the directives. Link phase To make the view dynamic, Angular then runs a link function for each directive. The link functions typically creates listeners on the DOM or the model. These listeners keep the view and the model in sync at all times. So we’ve got the compile phase, which deals with transforming the template, and the link phase, which deals with modifying the data in the view. Along these lines, the primary difference between the compile and link functions in directives is that compile 126 | Chapter 6: Directives functions deal with transforming the template itself, and link functions deal with mak‐ ing a dynamic connection between model and view. It is in this second phase that scopes are attached to the compiled link functions, and the directive becomes live through data binding. These two phases are separate for performance reasons. Compile functions execute only once in the compile phase, whereas link functions are executed many times, once for each instance of the directive. For example, let’s say you use ng-repeat over your di‐ rective. You don’t want to call compile, which causes a DOM-walk on each ng- repeat iteration. Instead, you want to compile once, then link. While you should certainly learn the differences between compile and link and the capabilities of each, the majority of directives you’ll need to write will not need to trans‐ form the template; you’ll write mostly link functions. Let’s take a look at the syntax for each of these again to compare. For compile, we have: compile: function compile(tElement, tAttrs, transclude) { return { pre: function preLink(scope, iElement, iAttrs, controller) { ... }, post: function postLink(scope, iElement, iAttrs, controller) { ... } } } And for link, it is: link: function postLink(scope, iElement, iAttrs) { ... } Notice that one difference here is that the link function gets access to a scope but compile does not. This is because during the compile phase, the scope doesn’t exist yet. You do, however, have the ability to return link functions from the compile function. These link functions do have access to the scope. Notice also that both compile and link receive a reference to their DOM element and the list of attributes for that element. The difference here is that the compile function receives the template element and attributes from the template, and thus gets the t prefix. The link function receives them from the view instances created from the tem‐ plate, and thus gets the i prefix. This distinction only matters when the directive is within some other directive that makes copies of the template. The ng-repeat directive is a good example.
Here, the compile function will be called exactly once, but the link function will be called once per copy of my-widget—equal to the number of elements in things. So, if API Overview | 127 my-widget needs to modify something in common to all copies (instances) of my- widget, the right place to do this, for efficiency’s sake, is in a compile function. You will also notice that the compile function receives a transclude function as a property. Here, you have an opportunity to write a function that programmatically transcludes content for situations where the simple template-based transclusion won’t suffice. Lastly, compile can return both a preLink and a postLink function, whereas link specifies only a postLink function. preLink, as its name implies, runs after the compile phase, but before directives on the child elements are linked. Similarly, postLink runs after all the child element directives are linked. This means that if you need to change the DOM structure, you will do so in postLink. Doing it in the preLink will confuse the attachment process and cause an error. Scopes You will often want to access a scope from your directive to watch model values and make UI updates when they change, and to notify Angular when external events cause the model to change. This is most common when you’re wrapping some non-Angular component from jQuery, Closure, or another library, or implementing simple DOM events. Evaluate Angular expressions passed into your directive as attributes. When you want a scope for one of these reasons, you have three options for the type of scope you’ll get: 1. The existing scope from your directive’s DOM element. 2. A new scope you create that inherits from your enclosing controller’s scope. Here, you’ll have the ability to read all the values in the scopes above this one in the tree. This scope will be shared with any other directives on your DOM element that request this kind of scope and can be used to communicate with them. 3. An isolate scope that inherits no model properties from its parent. You’ll want to use this option when you need to isolate the operation of this directive from the parent scope when creating reusable components. You can create these scope configurations with the following syntax: Scope Type Syntax existing scope scope: false (this is the default if unspecified) new scope scope: true isolate scope scope: { /* attribute names and binding style */ } 128 | Chapter 6: Directives When you create an isolate scope, you don’t have access to anything in the parent scope’s model by default. You can, however, specify that you want specific attributes passed into your directive. You can think of these attribute names as parameters to the function. Note that while isolate scopes don’t inherit model properties, they are still children of their parent scope. Like all other scopes, they have a $parent property that references their parent. You can pass specific attributes from the parent scope to the isolate scope by passing a map of directive attribute names. There are three possible ways to pass data to and from the parent scope. We call these different ways of passing data “binding strategies.” You can also, optionally, specify a local alias for the attribute name. The syntax without aliases is in the following form: scope: { attributeName1: 'BINDING_STRATEGY', attributeName2: 'BINDING_STRATEGY', … } With aliases, the form is: scope: { attributeAlias: 'BINDING_STRATEGY' + 'templateAttributeName', … } The binding strategies are defined by symbols in Table 6-4: Table 6-4. Binding strategies Symbol Meaning @ Pass this attribute as a string. You can also data bind values from enclosing scopes by using interpolation {{}} in the attribute value. = Data bind this property with a property in your directive’s parent scope. & Pass in a function from the parent scope to be called later. These are fairly abstract concepts, so let’s look at some variations on a concrete example to illustrate. Let’s say that we want to create an expander directive that shows a title bar that expands to display extra content when clicked. It would look like Figure 6-2 when closed. Figure 6-2. Expander in closed state It would look like Figure 6-3 when opened. API Overview | 129 Figure 6-3. Expander in open state We would write it as follows:
{{text}}
The values for title (Click me to expand) and text (Hi there folks…), come from the enclosing scope. We could set this up with a controller like so: function SomeController($scope) { $scope.title = 'Click me to expand'; $scope.text = 'Hi there folks, I am the content + 'that was hidden but is now shown.'; } We can then write this directive as: angular.module('expanderModule', []) .directive('expander', function(){ return { restrict: 'EA', replace: true, transclude: true, scope: { title:'=expanderTitle' }, template: '
' + '
{{title}}
' + '
' + '
', link: function(scope, element, attrs) { scope.showMe = false; scope.toggle = function toggle() { scope.showMe = !scope.showMe; } } } }); And for styling, we’d do something like this: .expander { border: 1px solid black; width: 250px; } 130 | Chapter 6: Directives .expander > .title { background-color: black; color: white; padding: .1em .3em; cursor: pointer; } .expander > .body { padding: .1em .3em; } Let’s look at what each option in the directive is doing for us, in Table 6-5. Table 6-5. Functions of elements Function Name Description restrict: EA Invoke this directive as either an element or attribute. That is, … and
…
are equivalent. replace: true Replace the original element with the template we provide. transclude: true Move the original element’s content to another location in the provided template. scope: { title: =expanderTitle } Create a local scope property called title that is data bound to a parent-scope property declared in the expander-title attribute. Here, we’re renaming expanderTitle as title for convenience. We could have written scope: { expanderTitle: '=' } and referred to it as expanderTitle within our template instead. But in case other directives also have a title attribute, it makes sense to disambiguate our title in the API and just rename it for local use. Also notice here that the naming uses the same camel-case expansion as the directive names themselves do. template: <'div'> + … Declare the template to be inserted for this directive. Note that we’re using ng-click and ng-show to show/hide ourselves and ng-transclude to declare where the original content will go. Also note that transcluded content gets access to the parent scope, not the scope of the directive enclosing it. link: … Set up the showMe model to track the expander’s open/closed state and define the toggle() function to be called when users click on the title div. If we think it would make more sense to define the expander title in the template rather than in the model, we can use the string-style attribute passing denoted by an @ symbol in the scope declaration, like this: scope: { title:'@expanderTitle' }, In the template we can achieve the same effect with: {{text}} Note that with this @ strategy we could still data bind the title to our controller’s scope by using interpolation : {{text}} API Overview | 131 Manipulating DOM Elements The iElement or tElement passed to the directive’s link and compile functions are wrapped references to the native DOM element. If you have loaded the jQuery library, these are jQuery elements you’re already used to working with. If you’re not using jQuery, the elements are inside an Angular-native wrapper called jqLite. This API has a subset of jQuery that we need to create everything in Angular. For many applications, you can do everything you need with this API alone. If you need direct access to the raw DOM element you can get it by accessing the first element of the object with element[0]. You can see the full list of supported APIs in the Angular docs for angular.element() —the function you’d use to create jqLite-wrapped DOM elements yourself. It includes functions like addClass(), bind(), find(), toggleClass(), and so on. Again, these are all the most useful core functions from jQuery, but with a much smaller code footprint. In addition to the jQuery APIs, elements also have Angular-specific functions. These exist whether or not you’re using the full jQuery library. Table 6-6. Angular specific functions on an element Function Description controller(name) When you need to communicate directly with a controller, this function returns the controller attached to the element. If none exists for this element, it walks up the DOM and finds the nearest parent controller instead. The name parameter is optional and is used to specify the name of another directive on this same element. If provided, it will return the controller from that directive. The name should be in the camel-case format as with all directives. That is, ngModel instead of ng-model. injector() Gets the injector for the current element or its parent. This allows you to ask for dependencies defined for the modules in these elements. scope() Returns the scope of the current element or its nearest parent. inheritedData() As with the jQuery function data(), inheritedData() sets and gets data on an element in a leak-proof way. In addition to getting data from the current element, it will also walk up the DOM to find a value. As an example, let’s re-implement the previous expander example without the help of ng-show and ng-click. It would look like the following: angular.module('expanderModule', []) .directive('expander', function(){ return { restrict: 'EA', replace: true, transclude: true, scope: { title:'=expanderTitle' }, template: '
' + '
{{title}}
' + '
' + 132 | Chapter 6: Directives '
', link: function(scope, element, attrs) { var titleElement = angular.element(element.children().eq(0)); var bodyElement = angular.element(element.children().eq(1)); titleElement.bind('click', toggle); function toggle() { bodyElement.toggleClass('closed'); } } } }); We’ve removed the ng-click and ng-show directives from the template. Instead, to perform the desired action when users click on the expander title, we’ll create a jqLite element from the title element and bind the click event to it with a toggle() function as its callback. In toggle(), we’ll call toggleClass() on the expander body element to add or remove a class called closed, where we’d set the element to display: none with a class like this: .closed { display: none; } Controllers When you have nested directives that need to communicate with each other, the way to do this is through a controller. A may need to know about the elements inside it so it can show and hide them appropriately. The same would be true for a knowing about its elements, or a knowing about its elements. As previously shown, to create an API to communicate between directives, you can declare a controller as part of a directive with the controller property syntax: controller: function controllerConstructor($scope, $element, $attrs, $transclude) This controller function is dependency injected, so the parameters listed here, while potentially useful, are all optional—they can be listed in any order. They’re also only a subset of the services available. Other directives can have this controller passed to them with the require property syntax. The full form of require looks like: require: '^?directiveName' Explanations of the require string can be found in Table 6-7. API Overview | 133 Table 6-7. Options for required controllers Option Usage directiveName This camel-cased name specifies which directive the controller should come from. So if our directive needs to find a controller on its parent , we’d write it as myMenu. ^ By default, Angular gets the controller from the named directive on the same element. Adding this optional ^ symbol says to also walk up the DOM tree to find the directive. For the example, we’d need to add this symbol; the final string would be \^myMenu. ? If the required controller is not found, Angular will throw an exception to tell you about the problem. Adding a ? symbol to the string says that this controller is optional and that an exception shouldn’t be thrown if not found. Though it sounds unlikely, if we wanted to let s be used without a container, we could add this for a final require string of ?\^myMenu. As an example, let’s rewrite our expander directive to be used in a set called “accordion,” which ensures that when you open one expander, the others in the set automatically close. This looks something like Figure 6-4. Figure 6-4. Accordion component in multiple states First, let’s write the accordion directive that will do the coordination. We’ll add our controller constructor here with methods to do the coordination: appModule.directive('accordion', function() { return { restrict: 'EA', replace: true, transclude: true, template: '
', controller: function() { var expanders = []; 134 | Chapter 6: Directives this.gotOpened = function(selectedExpander) { angular.forEach(expanders, function(expander) { if (selectedExpander != expander) { expander.showMe = false; } }); } this.addExpander = function(expander) { expanders.push(expander); } } } }); We’ve defined an addExpander() function for expanders to call to register themselves. We’ve also created a gotOpened() function for the expanders to call so the accordion’s controller can know to close any other open expanders. In the expander directive itself, we’ll extend it to require the accordion’s controller from the parent element and call addExpander() and gotOpened() at appropriate times. appModule.directive('expander', function(){ return { restrict: 'EA', replace: true, transclude: true, require: '^?accordion', scope: { title:'=expanderTitle' }, template: '
' + '
{{title}}
' + '
' + '
', link: function(scope, element, attrs, accordionController) { scope.showMe = false; accordionController.addExpander(scope); scope.toggle = function toggle() { scope.showMe = !scope.showMe; accordionController.gotOpened(scope); } } } }); Notice that the controller in the accordion directive creates an API through which the expanders can all communicate. We can then write a template to use these, which will produce the end result in Figure 6-4. {{expander.text}} with an appropriate controller, of course: function SomeController($scope) { $scope.expanders = [ {title: 'Click me to expand', text: 'Hi there folks, I am the content that was hidden but is now shown.'}, {title: 'Click this', text: 'I am even better text than you have seen previously'}, {title: 'No, click me!', text: 'I am text that should be seen before seeing other texts'} ]; } Moving On As we’ve seen, directives let us extend HTML’s syntax and turn many application tasks into a do-what-I-mean declaration. Directives make reuse a breeze—from configuring your app, like with ng-model and ng-controller, to doing template tasks like ng- repeat and ng-view, to sky’s-the-limit reusable components such as data-grids, bubble- charts, tool-tips, and tabs. 136 | Chapter 6: Directives CHAPTER 7 Other Concerns In this chapter, we will take a look at some other useful features that are present in AngularJS, but weren’t covered at all or in depth in the chapters and examples so far. $location Up to now, you have seen quite a few examples of the $location service in AngularJS. Most of them would have been fleeting glances—an access here, set there. In this section, we will dive into what exactly the $location service in AngularJS is for, and when you should and shouldn’t use it. The $location service is a wrapper around the window.location that is present in any browser. So why would you want to use it instead of working directly with window.lo cation? Goodbye global state window.location is a prime example of global state (actually, both window and document objects in the browser are prime examples). The minute you have global state in your application, testing, maintaining and working with it becomes a hassle (if not now, then definitely in the long run). The $location service hides this nas‐ tiness (what we call global state), and allows you to test the browser’s location details by injecting mocks during your unit tests. API window.location gives you total access to the contents of the browser location. That is, window.location gives you the string while $location gives you nice, jQuery-like setters and getters to work with it in a clean way. 137 AngularJS integration If you use $location, you can use it however you want. But with window.loca tion, you would have to be responsible for notifying AngularJS of changes, and listen to changes as well. HTML5 integration The $location service is smart enough to realize when HTML5 APIs are available within a browser and use them. If they’re not available, it will fall back to the default usage. So when should you use the $location service? Any time you want to react to a change in the URL (that is not covered by the $routes, which you should primarily use for working with URL-based views), as well as effect a change in the current URL in the browser. Let’s consider a small example of how you would use the $location service in a real- world application. Consider a case where we have a datepicker, and when a date is selected, the app navigates to a certain URL. Let us take a look at how that might look: // Assume that the datepicker calls $scope.dateSelected with the date $scope.dateSelected = function(dateTxt) { $location.path('/filteredResults?startDate=' + dateTxt); // If this were being done in the callback for // an external library, like jQuery, then we would have to $scope.$apply(); }; To $apply, or Not to $apply? There is confusion amongst AngularJS developers about when $scope.$apply() should be called and when it shouldn’t. Recommendations and rumors on the Internet are rampant. This section will make it crystal clear. But first, let us try to put $apply in a simpler form. Scope.$apply is like a lazy worker. It is told to do a lot of work, and it is responsible for making sure that the bindings are updated and the view reflects all those changes. But rather than doing this work all the time, it does it only when it feels it has enough work to be done. In all other cases, it just nods, and notes the work for later. It only actually does the work when you get its attention and tell it explicitly to work. AngularJS does this internally at regular intervals within its lifecycle, but if the call comes from outside (say a jQuery UI event), scope.$apply just takes note, but does nothing. That is why we have to call scope.$apply to tell it, “Hey! You need to do this right now, and not wait!” Here are four quick tips about when (and how) to call $apply. 138 | Chapter 7: Other Concerns • DO NOT call it all the time. Calling $apply when AngularJS is happily ticking away (in its $digest cycle, as we call it) will cause an exception. So “better safe than sorry” is not the approach you want to use. • DO CALL it when controls outside of AngularJS (DOM events, external callbacks such as jQuery UI controls, and so on) are calling AngularJS functions. At that point, you want to tell AngularJS to update itself (the models, the views, and so on), and $apply does just that. • Whenever possible, execute your code or function by passing it to $apply, rather than executing the function and then calling $apply(). For example, execute the following code: $scope.$apply(function() { $scope.variable1 = 'some value'; executeSomeAction(); }); instead of the following: $scope.variable1 = 'some value'; executeSomeAction(); $scope.$apply(); While both of these will have the same effect, they differ in one significant way. The first will capture any errors that happen when executeSomeAction is called, while the latter will quietly ignore any such errors. You will get error notifications from An‐ gularJS only when you do the first. • Consider using something like safeApply: $scope.safeApply = function(fn) { var phase = this.$root.$$phase; if(phase == '$apply' || phase == '$digest') { if(fn && (typeof(fn) === 'function')) { fn(); } } else { this.$apply(fn); } }; You can monkey patch this into the topmost scope or the rootscope, and then use the $scope.$safeApply function everywhere. This has been under discussion, and hope‐ fully in a future release, this will be the default behavior. $location | 139 What are those other methods also available on the $location object? Table 7-1 contains a quick summary for you to use in a bind. Let us take a look at how the $location service would behave, if the URL in the browser was http://www.host.com/base/index.html#!/path?param1=value1#hashValue. Table 7-1. Functions on the $location service Getter Function Getter Value Setter Function absUrl() http://www.host.com/base/index.html#!/path?param1=value1#hashValue N/A hash() hashValue hash('newHash') host() www.host.com N/A path() /path path('/newPath') protocol() http N/A search() {'a’: ‘b'} search({'c’: ‘def'}) url() /path?param1=value1?hashValue url('/newPath?p2=v2') The Setter Function column in Table 7-1 has some sample values that denote the type of object the setter function expects. Note that the search() setter has a few modes of operation: • Calling search(searchObj) with an object basically denotes all the parameters and their values • Calling search(string) will set the URL params as q=String directly in the URL • Calling search(param, value) with a string and value sets (or calling with null removes) a particular search parameter in the URL Using any one of the setters does not mean that window.location will get changed in‐ stantly! The $location service plays well with the Angular lifecycle, so all changes to the location will accumulate and get applied together at the end of the cycle. So feel free to make those changes, one after the other, without fear that the user will see a URL that keeps flickering and changing underneath him. HTML5 Mode and Hashbang Mode The $location service can be configured using the $locationProvider (which can be injected, just like everything else in AngularJS). Of particular interest are two properties on this provider, which are: html5Mode A boolean value which dictates whether the $location service works in HTML5 mode or not 140 | Chapter 7: Other Concerns hashPrefix A string value (actually a single character) that is used as the prefix for Hashbang URLs (in Hashbang mode or legacy browsers in HTML5 mode). By default it is empty, so Angular’s hash is just ‘’. If the hashPrefix is set to ‘!’, then Angular uses what we call Hashbang URLs (! followed by the url). You might ask, just what are these modes? Well, pretend that you have this super awesome website at www.superawesomewebsite.com that uses AngularJS. Let’s say you have a particular route (with some parameters and a hash), such as / foo?bar=123#baz. In normal Hashbang mode (with the hashPrefix set to ‘!’), or in legacy browsers without HTML5 mode support, your URL would look something like: http://www.superawesomewebsite.com/#!/foo?bar=123#baz While in HTML5 mode, the URL would simply look like this: http://www.superawesomewebsite.com/foo?bar=123#baz In both cases, location.path() would be /foo, location.search() would be bar=123, and location.hash() would be baz. So if that is the case, why wouldn’t you want to use the HTML5 mode? The Hashbang approach works seamlessly across all browsers, and requires the least amount of configuration. You just need to set the hashBang prefix (! by default) and you are good to go. The HTML5 mode, on the other hand, talks to the browser URL through the use of HTML5 History API. The $location service is smart enough to figure out whether HTML5 mode is supported or not, and fall back to the Hashbang approach if necessary, so you don’t need to worry about additional work. But you do have to take care of the following: Server-side configuration Because HTML5 links look like any other URL on your application, you need to take care on the server side to route all links within your app to your main HTML (most likely, the index.html). For example, if your app is the landing page for su‐ perawesomewebsite.com, and you have a route /amazing?who=me in your app, then the URL that the browser would show is http://www.superawesomewebsite.com/ amazing?who=me+. When you browse through your app, this will be fine, as the HTML5 History API kicks in and takes care of things. But if you try to browse directly to this URL, your server will look at you as if you have gone crazy, as there is no such known resource on its side. So you would have to ensure that all requests to /amazing get redirected to /index.html#!/amazing. $location | 141 AngularJS will kick in from that point onward and take care of things. It will detect changes to the path and redirect to the correct AngularJS routes that were defined. Link rewriting You can easily specify URLs as follows: link Depending on whether you are using HTML5 mode or not, AngularJS will take care to redirect to /some?foo=bar or index.html#!/some?foo=bar, respectively. No additional steps are required on your part. Awesome, isn’t it? But the following types of links will not be rewritten, and the browser will perform a full reload on the page: a. Links that contain a target element such as the following: link b. Absolute links going to a different domain: link This is different because it is an absolute URL, while the previous example used the existing base URL. c. Links starting with a different base path when one is already defined: link Relative Links Be sure to check all relative links, images, scripts, and so on. You must either specify the URL base in the head of your main HTML file (), or you must use absolute URLs (starting with /) everywhere because relative URLs will be resolved to absolute URLs using the initial absolute URL of the document, which is often different from the root of the application. Running Angular apps with the History API enabled from document root is strongly encouraged, as it takes care of all relative link issues. AngularJS Module Methods The AngularJS Module is responsible for defining how your application is bootstrapped. It also declaratively defines the pieces of your application. Let us take a look at how it accomplishes this. Where’s the Main Method? Those of you coming from a programming language like Java or even Python might be wondering, where is that main method in AngularJS? You know, the one that bootstraps 142 | Chapter 7: Other Concerns everything, and is the first thing to get executed? The one that functions in JavaScript and instantiates and wires everything together, then tells your application to go run? AngularJS doesn’t have that. What it has instead is the concept of modules. Modules allow us to declaratively specify our application’s dependencies, and how the wiring and bootstrapping happens. The reason for this kind of approach is manifold: 1. It is declarative. That means it is written in a way that is easier to write and under‐ stand. It reads like English! 2. It is modular. It forces you to think about how you define your components and dependencies, and makes them explicit. 3. It allows for easy testing. In your unit tests, you can selectively pull in modules, and avoid the untestable portions of your code. And in your scenario tests, you can load additional modules, which can make working with some components easier. Let us first take a look at how you would use a module that you have defined, then take a look at how we would declare one. Say we have a module, in fact, the module for our application, called “MyAwesomeApp.” In my HTML, I could just add the following to the tag (or technically, any other tag): The ng-app directive tells AngularJS to bootstrap your application using the MyAwe‐ someApp module. So how would that module be defined? Well, for one, we recommend that you have separate modules for your services, directives, and filters. Your main module could then just declare the other modules as a dependency (just like we did in Chapter 4 with the RequireJS example). This makes it easier to manage your modules, as they are nice complete chunks of code. Each module has one and only one responsibility. This also allows your tests to load only the modules they care about, and thus reduces the amount of initialization that needs to happen. The tests can be small and focused. Loading and Dependencies Module loading happens in two distinct phases, and the functions reflect them. These are the Config and the Run blocks (or phases): The Config block AngularJS hooks up and registers all the providers in this phase. Because of this, only providers and constants can be injected into Config blocks. Services that may or may not have been initialized cannot be injected. AngularJS Module Methods | 143 The Run block Run blocks are used to kickstart your application, and start executing after the injector is finished creating. To prevent further system configuration from hap‐ pening from this point onwards, only instances and constants can be injected into Run blocks. The Run block is the closest you are going to find to a main method in AngularJS. Convenience Methods What can you do with a module? We can instantiate controllers, directives, filters, and services, but the module class allows you to do more, as you can see in Table 7-2: Table 7-2. Module configuration methods API Method Description config(configFn) Use this method to register work that needs to be done when the module is loading. constant(name, object) This happens first, so you can declare all your constants app-wide, and have them available at all configuration (the first method in this list) and instance methods (all methods from here on, like controller, service, and so on). controller(name, constructor) We have seen a lot of examples of this; it basically sets up a controller for use. directive(name, directiveFactory) As discussed in Chapter 6, this allows you to create directives within your app. filter(name, filterFactory) Allows you to create named AngularJS filters, as discussed in previous chapters. run(initializationFn) Use this method when you want to perform work that needs to happen once the injector is set up, right before your application is available to the user. value(name, object) Allows values to be injected across the application. service(name, serviceFactory) Covered in the next section. factory(name, factoryFn) Covered in the next section. provider(name, providerFn) Covered in the next section. You might realize that we are missing the details of three particular API calls—Factory, Provider, and Service—from the preceding table. There is a reason for that: it is quite easy to confuse the usage between the three, so we will dive into a small example that should better illustrate when (and how!) to use each one. The Factory The Factory API call is used whenever we have a class or object that needs some amount of logic or parameters before it can be initialized. A Factory is a function that is responsible for creating a certain value (or object). Let us take the example of a greeter function that needs to be initialized with its salutation: function Greeter(salutation) { this.greet = function(name) { 144 | Chapter 7: Other Concerns return salutation + ' ' + name; }; } The greeter factory would look something like: myApp.factory('greeter', function(salut) { return new Greeter(salut); }); and it would be called as: var myGreeter = greeter('Halo'); The Service What about services? Well, the difference between a Factory and a Service is that the Factory invokes the function passed to it and returns a result. The Service in‐ vokes “new” on the constructor method passed to it and returns the result. So the preceding greeter Factory could be replaced with a greeter Service as follows: myApp.service('greeter', Greeter); Every time I asked for a greeter, AngularJS would call the new Greeter() and return that. The Provider This is the most complicated (and thus most configurable, obviously) of the lot. The Provider combines both the Factory and the Service, and also throws in the benefit of being able to configure the Provider function before the injection system is fully in place (in the config blocks, that is). Let’s see how a modified greeter Service using the Provider might look: myApp.provider('greeter', function() { var salutation = 'Hello'; this.setSalutation = function(s) { salutation = s; } function Greeter(a) { this.greet = function() { return salutation + ' ' + a; } } this.$get = function(a) { return new Greeter(a); }; }); This allows us to set the salutation at runtime (for example, based on the language of the user). AngularJS Module Methods | 145 var myApp = angular.module(myApp, []).config(function(greeterProvider) { greeterProvider.setSalutation('Namaste'); }); AngularJS would internally call $get whenever someone asked for an instance of the greeter object. Warning! There is a slight, but significant difference between using: angular.module('MyApp', [...]) and: angular.module('MyApp') The difference is that the first creates a new Angular module, pulling in the module dependencies listed in the square brackets ([…]). The second uses the existing module that has already been defined by the first call. So you should make sure that you use the following code only once in your entire application: angular.module('MyApp', [...]) // Or MyModule, if you are modularizing your app If you do not plan to save it to a variable and refer to it across your application, then use angular.module(MyApp) in the rest of the files to ensure you get a handle to the correct AngularJS module. Everything on the module must be defined by accessing the variable, or be added on the spot where the module has been defined. Communicating Between Scopes with $on, $emit, and $broadcast AngularJS scopes have a very hierarchical and nested structure. There is one main $rootScope (per Angular app or ng-app, that is), which all other scopes either inherit, or are nested under. Quite often, you will find that scopes don’t share variables or do not prototypically inherit from one another. In such a case, how do you communicate between scopes? One option is creating a service that is a singleton in the scope of the app, and processing all inter-scope com‐ munication through that service. There is another option in AngularJS: communicating through events on the scope. There are some restrictions; for example, you cannot generally broadcast an event to all watching scopes. You have to be selective in whether you are communicating to your parents or to your children. But before we discuss that, how do you listen to these events? Here is an example where our scope on any Star System is waiting and watching for an event we call “planetDes‐ troyed.” 146 | Chapter 7: Other Concerns scope.$on('planetDestroyed', function(event, galaxy, planet) { // Custom event, so what planet was destroyed scope.alertNearbyPlanets(galaxy, planet); }); Where do these additional arguments to the event listener come from? Let’s take a look at how an individual planet could communicate with its parent Star System. scope.$emit('planetDestroyed’, scope.myGalaxy, scope.myPlanet); The additional arguments to $emit are passed on as function parameters to the listener functions. Also, $emit communicates only upwards from its current scope, so the poor denizens of the planet (if they had a scope to themselves) would not be notified if their planet was being destroyed. Similarly, if a Galaxy wanted to communicate downwards to its child, the Star System scope, then it could communicate as follows: scope.$emit('selfDestructSystem', targetSystem); Then all Star Systems listening for the event could look at the target system, and decide if they should self-destruct, using these commands: scope.$on('selfDestructSystem', function(event, targetSystem) { if (scope.mySystem === targetSystem) { scope.selfDestruct(); // Go Ka-boom!! } }); Of course, as the event propagates all the way up (or down), it might become necessary at a certain level or scope to say, “Enough! You shall not PASS!” or to prevent what the event does by default. The event object passed to the listener has functions to handle all of the above, and more, so let us take a quick look at what you can get up to with the event object in Table 7-3. Table 7-3. Event object properties and methods Property of event Purpose event.targetScope The scope which emitted or broadcasted the event originally event.currentScope The scope currently handling the event event.name The name of the event event.stopPropagation() A function which will prevent further event propagation (this is available only for events that were $emitted event.preventDefault() This actually doesn’t do anything but set defaultPrevented to true. It is up to the implementer of the listeners to check on defaultPrevented before taking action event.defaultPrevented true if preventDefault was called Communicating Between Scopes with $on, $emit, and $broadcast | 147 Cookies Before long, you will encounter a situation in your application (provided it is sufficiently large and complex) where you need to store some kind of state across users’ sessions on the client side. You might remember (or have nightmares) about working with plain- text cookies through the document.cookie interface. Thankfully, many years have passed since then, and HTML5 APIs are available in almost all the modern browsers that are currently out there. Moreover, AngularJS provides you with a nice $cookie and $cookieStore API to work with cookies. Both services play nice with HTML5 cookies, in that they use HTML5 APIs when available, and default to working with document.cookies when they are not. Either way, you get to use the same API calls. Let’s take a look at the $cookies service first. $cookies is simply an object. It has keys and values. Adding a key and its corresponding value to the object adds the information to the cookie, and removing it from the object deletes that particular cookie. It’s as simple as that. But most of the time, you would not want to work directly at the $cookies level. Working directly at the cookies level would mean doing string manipulation and parsing your‐ self, and converting data to and from objects. For those cases, we have the $cookieS tore, which provides a programmatic way of writing and removing cookies. So what would a Search Controller that remembers the last five search results using the $cook ieStore look like? function SearchController($scope, $cookieStore) { $scope.search = function(text) { // Do the search here … // Get the past results, or initialize an empty array if nothing found var pastSearches = $cookieStore.get('myapp.past.searches') || []; if (pastSearches.length > 5) { pastSearches = pastSearches.splice(0); } pastSearches.push(text); $cookieStore.put('myapp.past.searches', pastSearches); }; } Internationalization and Localization You might have heard people throw about both terms when it comes to supporting your application in different languages. But there is a slight difference between the two. Con‐ sider a simple application that is a portal into your bank balance. Every time you come into the application, it displays one and only one thing: 148 | Chapter 7: Other Concerns Greetings! The balance in your account as of 10/25/2012 is $XX,XXX. Now, obviously, the preceding code is targeted at an American audience. But what if we wanted this application to be available in the UK as well (just so that the language itself doesn’t change)? Britain uses a different date format and currency symbol, but you don’t want your code to undergo a change every time you need the application to support a new locale (in this case, en_US and en_UK). This process of abstracting out the date/time format, as well as the currency symbol, from your coding logic is known as Interna‐ tionalization (or i18n—the 18 denoting the number of letters between i and n in the word). What if we wanted to support the application in Hindi? Or Russian? In addition to the date format and the currency symbol (and formatting), even the strings used in the UI would have to change. This process of providing translations and localized strings for the abstracted bits in various locales is known as Localization (or L10n—with a capital L to differentiate between i and l). What Can I Do in AngularJS? AngularJS supports i18n/L10n for the following filters out of the box: • currency • date/time • number There is also pluralization support (for English as well as i18n/L10n) with the ngPlur alize directive. All of this pluralization support is handled and managed by the $locale service, which manages the locale-specific rule sets. The $locale service works off of locale IDs, which generally consist of two parts: the country code and the language code. For example, en_US and en_UK, denote English used in the US and the UK, respectively. Specifying a country code is optional, just specifying “en” is a valid locale code. How Do I Get It All Working? Getting L10n and i18n working in AngularJS is a three-step process: Index.html changes AngularJS requires you to have a separate index.html for each supported locale. Your server also needs to know which index.html it has to provide, depending on the user’s locale preferences (this could also be triggered from a client-side change, when the user changes his locale). Internationalization and Localization | 149 Creating localized rule sets The next step is creating an angular.js file for each supported locale, like (angular_en-US.js and angular_zh-CN.js). This involves concatenating the localization rules for each particular language (the default files for the preceding two locales would be angular-locale_en-US.js and angular-locale_zh-CN.js) at the end of the angular.js or the angular.min.js file. So your angular_en-US.js would contain the contents of angular.js first, followed by the contents of the angular- locale_en-US.js. Sourcing the localized rule sets The final step involves ensuring that your localized index.html refers to the localized rule set instead of the original angular.js file. So index_en-US.html should use angular-en_US.js and not angular.js. What about my UI strings, you ask? AngularJS currently doesn’t have its own full- fledged translation APIs yet, so you will have to come up with your own techniques and scripts to get the UI strings translated. This could be something that parses your HTML for strings, and is then fed to a translator to churn out an HTML for each language, or something much more complex and specific based on your need. Common Gotchas Translation Length You design your UI so that it shows June 24, 1988 in a div that has been painstakingly sized to fit it just right. And then you open your UI in Spanish. 24 de junio de 1988 just doesn’t fit in that same space anymore… When internationalizing your apps, keep in mind that the lengths of your strings might change drastically from language to language. Design your CSS accordingly, and do thorough testing across the various languages. (Don’t forget that right to left languages also exist!) Timezones The AngularJS date/time filter picks up the timezone settings from the browser. So depending on the timezone of the computer, different people might see different information. Neither JS nor AngularJS have any built-in support to display time with a timezone specified by the developer. Sanitizing HTML & the Sanitize Module AngularJS takes its security seriously, and tries to make all efforts to ensure that most attack vectors are minimized. One of the attack vectors revolves around the injection of unsafe HTML content into your webpage and using that to trigger a cross-site or injection attack. 150 | Chapter 7: Other Concerns Consider the example where we have a variable on the scope called myUnsafeHTMLCon tent. OnMouseOver modifies the contents of the element to “PWN3D!” if the HTML is used as is: $scope.myUnsafeHTMLContent = '

an html' + 'click here' + 'snippet

'; The default behavior in AngularJS, when you have some HTML content in a variable and try to bind to it, would result in AngularJS escaping your content and printing it as is. So the HTML content ends up getting treated as pure text. Therefore:
will result in:

an html click here snippet

getting rendered as text on your web page. But what if you wanted to render the contents of myUnsafeHTMLContents as HTML in your AngularJS app? In such a case, AngularJS has additional directives (and a service, $sanitize, to boot) to allow you to render the HTML in both a safe and unsafe manner. Let us first take the example where you want to be safe (as you normally should be!), and render the HTML, taking care to get rid of most possible attack vectors in the HTML. You would use the ng-bind-html directive in such a case. The ng-bind-html, ng-bind-html-unsafe, and linky filter all are in the ngSanitize module. You will need to include angular-sanitize.js (or .min.js) in your script dependencies, and then add a module de‐ pendency to ngSanitize, before any of these work. So what happens when we use the ng-bind-html directive on the same myUnsafeHTML Content, like so?
The output in such a case would be the following: an html _click here_ snippet The important things to note are that the style tag (with color blue), and the onmouse over handler on the tag are both removed by AngularJS. They are deemed unsafe, and thus dropped. Sanitizing HTML & the Sanitize Module | 151 Finally, if you decide that you really want the contents of myUnsafeHTMLContent ren‐ dered as is, either because you really trust the source of the content, or for some other reason, then you can use the ng-bind-html-unsafe directive:
The output in such a case would be the following: an html _click here_ snippet The color of the text is blue (as per the style attached to the p tag), and the click here does have an onmouseover registered on it. So the minute your mouse strays anywhere near the click here text, the output would change to: an html PWN3D! snippet As you can see, this is quite unsafe in reality, so be absolutely certain that this is what you want when you decide to use the ng-bind-html-unsafe directive. Someone could just as easily read the user’s information and send it to his or her servers. Linky The linky filter is also present in the ngSanitize module, and basically allows you to add it to HTML content that is being rendered and convert links that are present in the HTML to anchor tags. It is quite simple to use, so let us take a look at an example: $scope.contents = 'Text with links: http://angularjs.org/ & mailto:us@there.org'; Now, if you use the following binding:
this would result in the contents of the HTML getting printed as: Text with links: http://angularjs.org/ & mailto:us@there.org Now let’s take a look at what happens when we use the linky filter:
The linky filter goes through the text contents and adds tags to all URLs and mailto links it finds, thus providing HTML content that the user can interact with: Text with links: http://angularjs.org/ & us@there.org 152 | Chapter 7: Other Concerns CHAPTER 8 Cheatsheet and Recipes By now, we have covered pretty much all the different parts of the Angular, including directives, services, controllers, resources, and so much more. But even we know that sometimes just reading about it isn’t enough. And sometimes we don’t care about how any of that works, we just want to know how to do that one thing with AngularJS? In this chapter, we take a stab at giving complete coding samples (with little bits of info and pointers to explain what is happening) for some common problems we tackle in most web apps. They are in no particular order, so feel free to jump to whichever ones you care about, or go through them in order. You are the boss! The examples covered in this chapter include: 1. Wrapping a jQuery Datepicker 2. The Teams List App: Filtering and Controller Communication 3. File Upload in AngularJS 4. Using socket.IO 5. A Simple Pagination Service 6. Working with Servers Wrapping a jQuery Datepicker This example can be found in chapter8/datepicker on our GitHub page. Even before we jump into the code, we have to decide how our component is going to look and work. Let’s say we want to define our datepicker in HTML as follows: 153 That is, we want to modify the Input field by adding an attribute datepicker, and adding some more functionality to it (like data binding with the model and the ability to be notified when a date is selected). So how would we go about it? We will re-use existing functionality, the jQuery UI’s datepicker, instead of building a datepicker from scratch. We just need to hook it up to AngularJS and latch onto the hooks it provides: angular.module('myApp.directives', []) .directive('datepicker', function() { return { // Enforce the angularJS default of restricting the directive to // attributes only restrict: 'A', // Always use along with an ng-model require: '?ngModel', scope: { // This method needs to be defined and // passed in to the directive from the view controller select: '&' // Bind the select function we refer to the // right scope }, link: function(scope, element, attrs, ngModel) { if (!ngModel) return; var optionsObj = {}; optionsObj.dateFormat = 'mm/dd/yy'; var updateModel = function(dateTxt) { scope.$apply(function () { // Call the internal AngularJS helper to // update the two-way binding ngModel.$setViewValue(dateTxt); }); }; optionsObj.onSelect = function(dateTxt, picker) { updateModel(dateTxt); if (scope.select) { scope.$apply(function() { scope.select({date: dateTxt}); }); } }; ngModel.$render = function() { // Use the AngularJS internal 'binding-specific' variable element.datepicker('setDate', ngModel.$viewValue || ''); }; element.datepicker(optionsObj); } 154 | Chapter 8: Cheatsheet and Recipes }; }); Most of the code is pretty straightforward, but let us walk through some of the more important bits: ng-model We get an ng-model attribute passed into the linking function of the directive. The ng- model (which is mandatory for the directive to function because of the require attribute inside the directive definition) allows us to define how the attribute and object linked to the ng-model behave in the context of the directive. There are two things you need to pay attention to: ngModel.$setViewValue(dateTxt) This is called when something external to AngularJS (in this case, the onSelect of the jQuery UI datepicker) happens. This lets AngularJS know that it has to update the model. This is usually called when a DOM event happens. ngModel.$render This is the other part to the ng-model. This tells Angular how to update the view when the model changes. In our case, we just pass on to the jQuery UI that the datepicker value has changed. Binding select Instead of using the attribute value and evaluating it as a string against the scope (in which case, nested functions and objects won’t be accessible), we use function binding (the “&” scope binding). This creates a new function on the scope called select, which takes one argument—an object. Each key in this object must match an argument speci‐ fied in the HTML where the directive is used. The value for that key will be the value passed to the function as that argument. The added advantage is that this decouples the controller implementation from having to know anything about the DOM or the di‐ rective. The callback function just performs its behavior given certain arguments, and does not need to know about the binding or the updates. Calling select Notice that we pass in an optionsObj to the datepicker, with an onSelect function. jQuery UI is responsible for calling the onSelect function, which will usually happen outside of AngularJS’ execution context. Of course, when functions like onSelect are called, AngularJS has no clue. It is up to us to let AngularJS know that it needs to act on stuff. How do we do that? By using scope.$apply. Wrapping a jQuery Datepicker | 155 Now we could just as easily do the $setViewValue and call the scope.select outside scope.$apply, and then just call scope.$apply(). But then any exceptions that happen in either of these two steps are silently dropped. If they happen within a scope.$ap ply function, then they are captured by AngularJS. The Rest of the Example To complete the example, let us take a look at our controller code, and then the HTML to get it working: var app = angular.module('myApp', ['myApp.directives']); app.controller('MainCtrl', function($scope) { $scope.myText = 'Not Selected'; $scope.currentDate = ''; $scope.updateMyText = function(date) { $scope.myText = 'Selected'; }; }); Pretty simple stuff. We declare a controller, set some scope variables, and then create a scope method (updateMyText) that we will later use for binding to the on-select event of the datepicker. On to the HTML next: 156 | Chapter 8: Cheatsheet and Recipes
{{myText}} - {{currentDate}} Notice how the select attribute is specified. There is no value “date” on the scope. But because of the way we have set up our function binding in the directive, AngularJS now knows that the function will take an argument, whose name will be “date.” This is what we specified as an object when the onSelect of the datepicker is called. For the ng-model, we specify $parent.currentDate instead of currentDate. Why? Because our directive creates an isolated scope so that we can have the select function bound. This makes it so that the currentDate is no longer linked by ng-model even if we set it. So we have to explicitly tell AngularJS that the currentDate it needs to refer to is not in the isolated scope, but in its parent scope. With this, when you load it up in your browser, you would see a text box that, when clicked, exposes the jQuery UI datepicker. On select, it updates the text on the screen from “Not Selected” to “Selected,” and your date. The date in the input field is also updated. The Teams List App: Filtering and Controller Communication In this example, we tackle multiple things at the same time, but there are two major takeaways: 1. How do you use filters—especially in a clean, simple way—with repeaters? 2. How do you communicate between controllers that do not share an inheritance relation? The app itself is quite simple. There is data, which is a list of teams from various sport, such as basketball, football (the NFL kind, not the soccer kind), and hockey. For each of these teams, we have the name, the city, the sport, and whether the team is featured or not. What we want to do is display this list, and also display filters on the left that immediately update the list as you modify them. We are going to have two controllers: one for storing the data, and the other to work with the filters. And we are going to use a service to communicate the changes to the filter between the ListCtrl and the FilterCtrl. Let us take a look at the service first, which is going to drive the application: angular.module('myApp.services', []). factory('filterService', function() { The Teams List App: Filtering and Controller Communication | 157 return { activeFilters: {}, searchText: '' }; }); Whoa. That’s it, you ask? Yes. What we are doing here is leveraging the fact that Angu‐ larJS services are singleton (that’s singleton with a small “s”—singleton within the scope, but not globally visible or accessible). When we declare the filterService, we are guar‐ anteed to have only one instance of the filterService for the entire myApp. We then end up using the filterService as a communication channel between the Fil terCtrl and the ListCtrl, as both can bind to it and access stuff as it is updated. Both of these controllers are actually dead simple, as they do nothing but simple assignment: var app = angular.module('myApp', ['myApp.services']); app.controller('ListCtrl', function($scope, filterService) { $scope.filterService = filterService; $scope.teamsList = [{ id: 1, name: 'Dallas Mavericks', sport: 'Basketball', city: 'Dallas', featured: true }, { id: 2, name: 'Dallas Cowboys', sport: 'Football', city: 'Dallas', featured: false }, { id: 3, name: 'New York Knicks', sport: 'Basketball', city: 'New York', featured: false }, { id: 4, name: 'Brooklyn Nets', sport: 'Basketball', city: 'New York', featured: false }, { id: 5, name: 'New York Jets', sport: 'Football', city: 'New York', featured: false }, { id: 6, name: 'New York Giants', sport: 'Football', city: 'New York', featured: true }, { id: 7, name: 'Los Angeles Lakers', sport: 'Basketball', city: 'Los Angeles', featured: true }, { id: 8, name: 'Los Angeles Clippers', sport: 'Basketball', city: 'Los Angeles', featured: false }, { id: 9, name: 'Dallas Stars', sport: 'Hockey', city: 'Dallas', featured: false }, { id: 10, name: 'Boston Bruins', sport: 'Hockey', city: 'Boston', featured: true } ]; }); 158 | Chapter 8: Cheatsheet and Recipes app.controller('FilterCtrl', function($scope, filterService) { $scope.filterService = filterService; }); You might be wondering, where is the complexity? AngularJS does make it this easy. All we have left to do is to pull this all together in the template:
Search:

Sport:

{{sport}} The Teams List App: Filtering and Controller Communication | 159

City:

{{city}}

Featured:

Name	Sport	City	Featured
{{team.name}}	{{team.sport}}	{{team.city}}	{{team.featured}}

160 | Chapter 8: Cheatsheet and Recipes There are really only four items of interest in this entire HTML template. Everything else you have seen a few dozen times by now (even these items have been there in some form or another). Let us go over them one by one. The Search Box The search box just binds to the filterService.searchText field using an ng-model. In and of itself, it is nothing noteworthy, but the way this is later used in the filter makes this step essential. The Combo Boxes There are two combo boxes, even though we have only highlighted the first. Both of them work the same way. They are both bound to filterService.activeFil ters.sports or city (depending on the box), which basically sets the sports (or city) property on the filters object in the filtersService. The Check Box The check box binds to filterService.activeFilters.featured. The thing to note is that when featured is checked, we want to show only those teams with featured = true. When it is unchecked, we want to show teams with featured = true and fea tured = false. For this, we use the ng-false-value="" directive to say that the fea tured filter should be cleared when the checkbox is unchecked. The Repeater Let us take a look at the ng-repeat statement one more time: "team in teamsList | filter:filterService.activeFilters | filter:filterService.searchText" The first part is the same as always. It is the two new filters that make all the difference. The first filter tells AngularJS to filter the list using filterService.activeFilters. This basically takes each property in the object filters and ensures that each item in the repeater matches corresponding properties in the filter. So if activeFilters[city] = Dallas, then only those items in the repeater with city = Dallas will be selected. If there are multiple filters, then all of them would have to match. The second filter is a textual match filter. It basically selects only those items that have the value of filterService.searchText present in any of their values. So it will do a match across cities, team names, sports, and featured. The Teams List App: Filtering and Controller Communication | 161 File Upload in AngularJS Another common use case we have seen is to support uploading of files from within an AngularJS app. While it is possible to support this by building on the existing input type “file” that is present in HTML, for the purpose of this example, we are going to extend existing solutions for file upload. A great one is BlueImp’s File Upload, which uses jQuery and jQueryUI (or Bootstrap). Their API is dead simple, which also makes our directive super easy. So let us start with the directive declaration: angular.module('myApp.directives', []) .directive('fileupload', function() { return { restrict: 'A', scope: { done: '&', progress: '&' }, link: function(scope, element, attrs) { var optionsObj = { dataType: 'json' }; if (scope.done) { optionsObj.done = function() { scope.$apply(function() { scope.done({e: e, data: data}); }); }; } if (scope.progress) { optionsObj.progress = function(e, data) { scope.$apply(function() { scope.progress({e: e, data: data}); }); } } // the above could easily be done in a loop, to cover // all API's that Fileupload provides element.fileupload(optionsObj); } }; }); 162 | Chapter 8: Cheatsheet and Recipes This code allows us to define our directive in a very simple manner, as well as add hooks for onDone and onProgress. We use function binding so that AngularJS always calls the right methods and uses the right scope. This is done by the isolated scope declaration, which has two bindings: one for pro gress and one for done. This creates a function which takes a single argument (an object) on the scope. For instance, scope.done takes an object as an argument. This object has two keys, e and data. These are passed along as arguments to the original function, which we will see in the next section. Let’s take a look at our HTML to see how we would use this: File Upload: Our input tag just has the following additions: fileupload This marks the input tag as a file upload element. data-url This is used by the FileUpload plug-in to decide where to upload the file to. In our example, we assume there is a server API waiting at /server/uploadFile to process the data it sends. multiple The multiple attribute tells the directive (and the fileupload widget) to allow it to select multiple files at once. We get this for free from the plug-in without needing to write a single additional line of code. Again, this is a built-in plug-in bonus. done This is the AngularJS function to call when the plug-in finishes uploading the se‐ lected file. We could add similar ones for progress if we wanted to. This also speci‐ fies the two arguments that our directive calls. So what does the controller backing this look like? Pretty much what you would expect it to look like: var app = angular.module('myApp', ['myApp.directives']); app.controller('MainCtrl', function($scope) { $scope.uploadFinished = function(e, data) { console.log('We just finished uploading this baby...'); }; }); And with that, we have a simple, working, reusable file upload directive. Using Socket.IO A common requirement for the web nowadays is real-time web applications, which need to be updated as soon as the data on the server is updated. Previously used tech‐ niques such as polling have been found lacking, and sometimes we just want to open a socket to our client and communicate. Socket.IO is a brilliant library that allows you to do just that, and uses a dead simple, event-based API to allow you to develop real-time web apps. We are going to develop 164 | Chapter 8: Cheatsheet and Recipes a real-time, anonymous broadcast system (think Twitter, without usernames) that allows users to broadcast a message to all Socket.IO’s users and see all the messages. Nothing will be stored, so all messages will only be alive for as long as a given user is active, but that will be sufficient to demonstrate how nicely Socket.IO can integrate into AngularJS. Right off, we are going to wrap Socket.IO into a nice AngularJS service. By doing so, we can ensure that: • Socket.IO events are noticed and handled within the AngularJS lifecycle • It becomes easy to test the integration later var app = angular.module('myApp', []); // We define the socket service as a factory so that it // is instantiated only once, and thus acts as a singleton // for the scope of the application. app.factory('socket', function ($rootScope) { var socket = io.connect('http://localhost:8080'); return { on: function (eventName, callback) { socket.on(eventName, function () { var args = arguments; $rootScope.$apply(function () { callback.apply(socket, args); }); }); }, emit: function (eventName, data, callback) { socket.emit(eventName, data, function () { var args = arguments; $rootScope.$apply(function () { if (callback) { callback.apply(socket, args); } }); }) } }; }); We are just wrapping the two functions we care about, which are the on event and broadcast event methods of the Socket.IO API. There are a bunch more, and they can be wrapped in a similar manner. We are going to have a simple index.html, which shows a textbox with a send button and a list of messages. In this example, we do not keep track of who sends the messages or when they are sent. Using Socket.IO | 165 Broadcast
• {{msg}}
Let’s go to our MainCtrl (this is part of app.js), which is where we pull this all together: function MainCtrl($scope, socket) { $scope.message = ''; $scope.messages = []; // When we see a new msg event from the server socket.on('new:msg', function (message) { $scope.messages.push(message); }); // Tell the server there is a new message $scope.broadcast = function() { socket.emit('broadcast:msg', {message: $scope.message}); $scope.messages.push($scope.message); $scope.message = ''; }; } The controller itself is quite simple. It listens for events on the socket connection, and whenever the user presses the broadcast button, lets the server know that there is a new message. It also adds it to the message list to display immediately to the user. Then we have the final piece, the server. This is a NodeJS server that knows how to serve the app code, and also simultaneously create a Socket.IO server. var app = require('express')() , server = require('http').createServer(app) 166 | Chapter 8: Cheatsheet and Recipes , io = require('socket.io').listen(server); server.listen(8080); app.get('/', function (req, res) { res.sendfile(__dirname + '/index.html'); }); app.get('/app.js', function(req, res) { res.sendfile(__dirname + '/app.js'); }); io.sockets.on('connection', function (socket) { socket.emit('new:msg', 'Welcome to AnonBoard'); socket.on('broadcast:msg', function(data) { // Tell all the other clients (except self) about the new message socket.broadcast.emit('new:msg', data.message); }); }); You could easily expand this later to handle more messages and more intricate struc‐ tures, but this example lays the foundation on which you can implement socket con‐ nections between your client and server. The app is very simple. It does not do any validation (whether the messages are empty), but it does have the HTML sanitization that AngularJS provides by default. It does not handle complex messages, but it does offer a fully working end-to-end Socket.IO im‐ plementation integrated into AngularJS that you can now build your work off of. A Simple Pagination Service A very common use case for most web apps is to display a list of items. More often than not, we have more data than can be reasonably displayed on a single page. In such a case, we want to display the data in a paginated manner, with an ability to move to the next and previous pages. Since this is a common requirement throughout the app, it makes sense to extract this functionality into a common, reusable Paginator service. Our Paginator service (a very simple implementation) is going to allow users of the service to tell the service how to fetch the data, given an offset and limit, as well as the page size. It will internally handle all the logic of figuring out which items to fetch, which page is next, whether there is a next page, and so on. This service could be extended further to cache items within the service, but that is left as an exercise for the user. All our example will entail is storing the currentPageI tems field in a cache, retrieving it from there if it is available, and going to the fetch Function otherwise. A Simple Pagination Service | 167 Let’s take a look at the service implementation: angular.module(‘services’, []).factory('Paginator', function() { // Despite being a factory, the user of the service gets a new // Paginator every time he calls the service. This is because // we return a function that provides an object when executed return function(fetchFunction, pageSize) { var paginator = { hasNextVar: false, next: function() { if (this.hasNextVar) { this.currentOffset += pageSize; this._load(); } }, _load: function() { var self = this; fetchFunction(this.currentOffset, pageSize + 1, function(items) { self.currentPageItems = items.slice(0, pageSize); self.hasNextVar = items.length === pageSize + 1; }); }, hasNext: function() { return this.hasNextVar; }, previous: function() { if(this.hasPrevious()) { this.currentOffset -= pageSize; this._load(); } }, hasPrevious: function() { return this.currentOffset !== 0; }, currentPageItems: [], currentOffset: 0 }; // Load the first page paginator._load(); return paginator; }; }); The Paginator service expects two arguments when it is called: a fetch function, and the size of each page. The fetch function expects the following signature: fetchFunction(offset, limit, callback); It will then be called with the correct offset and limit by the Paginator whenever it needs to fetch and display a certain page. Internal to the function, it can either slice the data 168 | Chapter 8: Cheatsheet and Recipes from a large array, or go to the server and make a call to fetch the data. When the data is available, the fetch function needs to call the callback function with it. Let us take a look at the spec for this, to clarify how we could use it when we have a large array with too many items returned to us. Note that this is a unit test. Because of the way it is implemented, we can test the service independent of any controller or XHR requests. describe('Paginator Service', function() { beforeEach(module('services')); var paginator; var items = [1, 2, 3, 4, 5, 6]; var fetchFn = function(offset, limit, callback) { callback(items.slice(offset, offset + limit)); }; beforeEach(inject(function(Paginator) { paginator = Paginator(fetchFn, 3); })); it('should show items on the first page', function() { expect(paginator.currentPageItems).toEqual([1, 2, 3]); expect(paginator.hasNext()).toBeTruthy(); expect(paginator.hasPrevious()).toBeFalsy(); }); it('should go to the next page', function() { paginator.next(); expect(paginator.currentPageItems).toEqual([4, 5, 6]); expect(paginator.hasNext()).toBeFalsy(); expect(paginator.hasPrevious()).toBeTruthy(); }); it('should go to previous page', function() { paginator.next(); expect(paginator.currentPageItems).toEqual([4, 5, 6]); paginator.previous(); expect(paginator.currentPageItems).toEqual([1, 2, 3]); }); it('should not go next from last page', function() { paginator.next(); expect(paginator.currentPageItems).toEqual([4, 5, 6]); paginator.next(); expect(paginator.currentPageItems).toEqual([4, 5, 6]); }); it('should not go back from first page', function() { paginator.previous(); A Simple Pagination Service | 169 expect(paginator.currentPageItems).toEqual([1, 2, 3]); }); }); The Paginator exposes currentPageItems on itself, which can then be bound from the templates on a repeater (or however else you want to display them). The hasNext() and hasPrevious() can be used to figure out when to show the Next and Previous Page links, and on click, it just needs to call next() or previous(), respectively. How would you use this with something that needs to fetch data from the server for each page? Here is what a possible controller that fetches search results from the server one page at a time could look like: var app = angular.module('myApp', ['myApp.services']); app.controller('MainCtrl', ['$scope', '$http', 'Paginator', function($scope, $http, Paginator) { $scope.query = 'Testing'; var fetchFunction = function(offset, limit, callback) { $http.get('/search', {params: {query: $scope.query, offset: offset, limit: limit}}) .success(callback); }; $scope.searchPaginator = Paginator(fetchFunction, 10); }]); The HTML page could use the Pagination service as follows:
• {{item}}
<< Prev Next >> Working with Servers and Login One final example will actually cover a multitude of scenarios, most or all of them linked with the $http resource. In our experience, the $http service is one of the core services in AngularJS. But it can be extended to do a lot of the common requirements of a web app, including: • Having a common error-handling point • Handling authorization and login redirects • Working with servers that don’t understand or speak JSON • Talking with external services (outside the same origin) via JSONP So in this (slightly contrived) example, we will have the skeleton of a full-fledged app that will: 1. Show all unrecoverable errors (Non 401s) in a butterbar directive that gets shown on all screens only when an error exists. 2. Have an ErrorService which will be used for communicating between the direc‐ tive, the view, and the controllers. 3. Fire an event (event:loginRequired) whenever the server responds with a 401. This will then get handled by a root controller that oversees the entire application. 4. Handle requests that need to be made to the server with some authorization headers that are specific to the current user. We will not go over the entire application (the routes, the templates, and so on), as most of those are fairly straightforward. We will highlight only the pieces that are relevant (so you can copy and paste that into your codebase and get started right away). These will be fully functional. If you want to revisit defining Services and Factories, jump to Chapter 7. If you want to take a look at how to work with servers, you can refer to Chapter 5. Let us first take a look at the Error service: var servicesModule = angular.module('myApp.services', []); servicesModule.factory('errorService', function() { Working with Servers and Login | 171 return { errorMessage: null, setError: function(msg) { this.errorMessage = msg; }, clear: function() { this.errorMessage = null; } }; }); Our error message directive, which is actually independent of the Error service, would just look for an alert message attribute, and then bind to it. It would conditionally show itself when the alert message is present. // USAGE:
angular.module('myApp.directives', []). directive('alertBar', ['$parse', function($parse) { return { restrict: 'A', template: '
' + '' + 'x' + '{{errorMessage}}
', link: function(scope, elem, attrs) { var alertMessageAttr = attrs['alertmessage']; scope.errorMessage = null; scope.$watch(alertMessageAttr, function(newVal) { scope.errorMessage = newVal; }); scope.hideAlert = function() { scope.errorMessage = null; // Also clear the error message on the bound variable. // Do this so that if the same error happens again // the alert bar will be shown again next time. $parse(alertMessageAttr).assign(scope, null); }; } }; }]); We would then add the alert bar to the HTML as follows:
We need to ensure that the ErrorService is saved on the scope of the controller as “errorService” before we add the preceding HTML. That is, if RootController was the controller responsible for having the AlertBar, then: 172 | Chapter 8: Cheatsheet and Recipes app.controller('RootController', ['$scope', 'ErrorService', function($scope, ErrorService) { $scope.errorService = ErrorService; }); That gives us a decent framework to show and hide errors and alerts. Now let us see how we can tackle the various status codes that the server can throw at us, through the use of an interceptor: servicesModule.config(function ($httpProvider) { $httpProvider.responseInterceptors.push('errorHttpInterceptor'); }); // register the interceptor as a service // intercepts ALL angular ajax HTTP calls servicesModule.factory('errorHttpInterceptor', function ($q, $location, ErrorService, $rootScope) { return function (promise) { return promise.then(function (response) { return response; }, function (response) { if (response.status === 401) { $rootScope.$broadcast('event:loginRequired'); } else if (response.status >= 400 && response.status < 500) { ErrorService.setError('Server was unable to find' + ' what you were looking for... Sorry!!'); } return $q.reject(response); }); }; }); Now all that needs to happen is for some controller somewhere to listen for a loginRe quired event, and redirect to the login page (or do something more complex, like display a modal dialog with login options). $scope.$on('event:loginRequired', function() { $location.path('/login'); }); That just leaves requests that will need authorization. Let us just say that all requests that require authorization will need a header—“Authorization”—which will have a value that is specific for the current user that is logged in. Since this will change every time, we cannot use default transformRequests, as those are config level changes. We will instead wrap the $http service, and create our own AuthHttp service. We will also have an Authentication service that is responsible for storing the user’s auth information (fetched however you want, normally as part of the login process). The AuthHttp service will refer to this Authentication service and add the necessary headers to authorize the requests. Working with Servers and Login | 173 // This factory is only evaluated once, and authHttp is memorized. That is, // future requests to authHttp service return the same instance of authHttp servicesModule.factory('authHttp', function($http, Authentication) { var authHttp = {}; // Append the right header to the request var extendHeaders = function(config) { config.headers = config.headers || {}; config.headers['Authorization'] = Authentication.getTokenType() + ' ' + Authentication.getAccessToken(); }; // Do this for each $http call angular.forEach(['get', 'delete', 'head', 'jsonp'], function(name) { authHttp[name] = function(url, config) { config = config || {}; extendHeaders(config); return $http[name](url, config); }; }); angular.forEach(['post', 'put'], function(name) { authHttp[name] = function(url, data, config) { config = config || {}; extendHeaders(config); return $http[name](url, data, config); }; }); return authHttp; }); Any request that requires authorization will be made via authHttp.get() instead of $http.get(). As long as the Authentication service is set with the right information, your calls will fly through with ease. We use a service for Authentication as well, so that the information is available throughout the app, without having to refetch it every time the route changes. That pretty much covers all the pieces we would need for this application. You should be able to just copy the code right out of here, paste into your application, and make it work for you. Good luck! Conclusion While this brings us to the end of our book, we are nowhere near close to covering everything about AngularJS. Our aim with this book was to provide a solid foundation from which one can begin her explorations and become comfortable with developing in AngularJS. To this extent, we covered all the basics (and some advanced topics), while providing as many examples as we could along the way. 174 | Chapter 8: Cheatsheet and Recipes Are we done? No. There is still a great amount to learn about how AngularJS operates under the covers. We didn’t touch upon creating complex, interdependent directives, for example. There is so much more out there, that three or even four books wouldn’t be enough. But we hope that this book gives you the confidence to be able to tackle much more complex requirements head on. We had a great time writing this book, and hope to see some amazing applications written in AngularJS out on the Internet. Conclusion | 175 We’d like to hear your suggestions for improving our indexes. Send email to index@oreilly.com. Index Symbols $apply, 138 $broadcast, 146 $emit, 146 $first, 22 $http, 42 $http service, 81, 101–106, 171–174 $index, 22 $last, 22 $locale, 149 $location best uses for, 138 changing views with, 38–41 HTML5 and Hashbang modes, 140 vs. window.location, 137 $locationProvider, 140 $middle, 22 $on, 146 $parent property, 129 $q, 113 $resource, 108, 111 $rootScope, 146 $route service, 38 $scope object, 13 $scope.isDisabled, 24 $templateCache, 125 $valid property, 46 $watch() function, 17, 29, 31 & (ampersand) symbol, 129 404 errors, 26 tags, 26 tags, 26 = (equal) symbol, 129 @ (at) symbol, 129 A Access-Control-Allow-Origin, 125 advanced optimization, 58 Angular expressions, 17 Angular Resource, 81 angular.element() function, 132 angular.module(MyApp, […]) vs. angular.mod‐ ule(MyApp), 146 AngularJS basic building blocks of, 11–46 client-side templates in, 2, 57 data binding in, 3 dependency injection in, 5 directives in, 5 integration with $location, 138 invoking, 11 Model View Controller (MVC) in, 3 vs. other apps, 2 AngularJS plug-in, 50 API calls, 144 application development, 47–74 Batarang extension for, 60 compilation, 57 177 debugging, 59 integration tests, 56 integration with RequireJS, 67 project organization, 47, 67 running your app, 51 solutions to common problems, 153–174 testing, 52, 66 tools for, 50 unit tests, 54 workflow optimization, 64 applications analyzing, 77–100 basic startup flow, 15 cache ability of, 15 ARIA semantic tags, 19 array-style injection, 59 asynchronous actions, 82 asynchronous requests, 112, 113 attack vectors, 151 attribute datepickers, 154 authentication service, 173 autofocus attribute, 43 automated testing, 56 autoWatch flag, 55 B back buttons, 41 banking attacks, 116 basic optimization, 58 Batarang, 60 bi-directional data binding, 29 binding strategies, 129 bitwise operations, 27 BlueImp’s File Upload, 162 bookmarks, 41 boolean logic, 27 bootstrap method, 143 bootstrap.js file, 69 boundaries, declaring, 12 bundled filters, 37 business logic, 78 butterbar directive, 90 C cacheable applications, 15 caching, 42, 105, 125 callbacks, 112 camel-cased names, 121 check boxes, 16, 161 child controller, 88 child scopes, 129 Chrome browser, 125 Chrome desktop apps, 41 classes, 2, 24 click event handler, 19 click notification, 20 client-side templates, 2, 57 Closure Compiler, 58 code minification, 57 code optimization, 58 combo boxes, 161 comparisons, 27 compilation, 57 compile property, 120, 126 computed results, 29 Config block, 143 configuration files, 49 controller property, 120 controller unit tests, 96 (see also unit tests) controllers adding with Yeoman, 66 basics of, 12, 13, 78 communication between, 157 defining, 14 file location of, 48 in Angular, 3, 7 nesting of, 28, 133 separating UI responsibilities with, 27 vs. modules, 33 working example of, 85 convenience methods, 102, 144 cookies, 117, 148 CORS, 42 credit card objects, 108 cross-browser compatibility, 20, 45 CSS classes and styles, 24–26 currency filter, 37, 149 custom error messages, 95 D data formatting with filters, 37 passing among scopes, 129 data binding and templates, 14–33 basics of, 3 178 | Index native speed, 31 strategies for, 129 date filter, 37 date/time localization, 149 datepickers, 154 debugger breakpoints, 31 debugging, 59 declarations, 111 declarative event handlers, 21 deepWatch, 29 default headers, 104 dependency injection basics of, 5 management of, 62, 67 organizing with modules, 33, 143 dependency loops, 31 deployment packages, 67 directive definition object, 122–125 directive factory function, 43 directives API overview, 120–135 basics of, 5, 79, 84 creating custom, 43, 90, 120 HTML validation and, 119 discounts, automatic application of, 31 display:block, 23 display:none, 23 do-what-I-mean declaration, 136 doA() function, 20 doB() function, 20 document.cookie interface, 148 DOM (Document Object Model) changing with directives, 43 manipulation in Angular, 3, 5, 79, 132 unit tests and, 21 domReady, 69 doSomething() function, 20 double-curly syntax interpolation, 12, 16, 24 E Edit Controller, 86 email app, 39 end-to-end tests, 56 errors 404 errors, 26 handling of, 115 input error, 95 login errors, 171 NullPointerException error, 27 Origin null is not allowed, 125 eval() function, 27 event handlers, 18 event handlers vs. directives, 20 event listeners, 2 event properties, 147 expressions, 26, 28 ExpressJS, 51 F Factory API call, 144 factory(), 35 file upload, 162–164 filters basics of, 8 creating, 37 formatting data with, 37 using with repeaters, 157 Firebug, 59 flow-of-control operators, 27 for loop, 27 form elements binding to model properties, 16 hiding/showing, 23 form validation controls, 45, 94 forward buttons, 41, 41 full propagation, 31 function binding, 155 G generic services, 35 GET requests, 116, 125 global namespace, 14, 20 global state, drawbacks of, 137 Google Closure, 58 Google’s content delivery network (CDN), 11 GutHub, 77 H Hashbang mode, 140 headers, setting, 104 Hello, World example, 2, 4 History API, 142 href attribute, 26 HTML Angular template files, 48 HTML extensions directives, 6 HTML sanitization, 150 Index | 179 HTML validation, 119 HTML5, 43, 119, 138, 140 HTML5 cookies, 148 HTTP headers, setting, 104 HTTP protocol, 42 I i18n/L10n, 149 IDs, 2, 19, 125 IE (Internet Explorer), 81, 122 if-else operator, 27 image tags, 26 index.html, 149 indices, 22 initialization process, 126 inline event handlers, 19 inline styles, 24 input, validation of, 45, 94 integration tests, 49, 56 internationalization, 148 isDisabled property, 24 isolate scopes, 128 item property, in shopping cart example, 7 J Jasmine tests, 49, 54, 96 Java, 12 JavaScript eval() function, 27 main method, 143 writing unobtrusive, 19 jqLite wrapper, 132 jQuery, 4, 102, 132 jQuery Datepickers, 153–157 JS library dependencies, 48 JS source files, 48 JSON, 171 JSON vulnerability, 116 JSONP, 42, 171 JSP, 3 K Karma, 52, 55, 56, 71 keyboard focus, 43 L Law of Demeter, 5 library, loading of, 11 link href values, 91 link property, 120, 126 links emailing, 41 relative links, 142 rewriting, 142 linky filter, 152 List Controller, 86, 91, 97 lists, 21, 157 loading, 143 localization, 148 logic avoiding in templates, 26, 79 business logic, 78 login errors, 171 looping constructs, 27 M main method, 143 malicious sites, 116 mandatory fields, 45 manual testing, 57 mathematics functions, 27 menus, conditional disabling of, 24 method calls, 102 minification, 57, 66 minimum/maximum field lengths, 95 mobile apps, 41, 58 mock data, 34 model data observing changes with, 29 publishing with scopes, 28, 128–131 storage of, 3 model objects, creating, 13, 108 model properties, binding elements to, 16 model variables, 12 Model View Controller (MVC) basics of, 3, 12 models as basis for apps, 79 basics of, 12, 78 model trees in Batarang, 60 module class, 144 modules creation of, 14 module methods, 142–146 number needed, 36 organization of, 143 180 | Index organizing dependencies with, 33 reasons for, 143 vs. controllers, 33 monkey patches, 34 mousedown event handler, 19 multiple browser testing, 52 multiple properties, watching, 33 N names/naming directives, 121 parameter name matching, 36 services, 35 namespaces for Angular, 119 providing, 14 native-speed data binding, 31 nav bars, 20 nested controllers, 28, 133 New Controller, 87 ng-app declaring boundaries with, 12, 15 function of, 7, 143 working example of, 90 ng-bind, 15 ng-class, 24, 92 ng-click, 18, 20 ng-controller DOM node association with, 28 function of, 6, 94 ng-dblclick, 18 ng-directive-name syntax, 119 ng-disabled, 46, 95 ng-eventhandler, 20 ng-hide, 23, 92 ng-href, 26, 91 ng-model bi-directional data binding, 29 binding elements with, 16 function of, 6 in jQuery wrap, 155 in shopping cart example, 7 ng-repeat for lists, 21, 161 function of, 7 priority property and, 122 working example of, 91, 92, 94 ng-show, 23, 92 ng-src, 26 ng-style, 24 ng-submit, 18, 92, 94 ng-transclude, 126 ng-view, 91 ngPluralize, 149 ngResource, 112 number filter, 37 number localization, 149 O object properties, 29, 33, 108 Object.observe(), 31 onclick, 18 ondblclick, 18 optimization, 58 optional fields, 45 order-independent arguments, 36 Origin null…, 125 P pagination service, 167–170 parameter name matching, 36 parameterization, 111 parent scopes, 129 parsing complexity, 34 password requirement, enforcing, 95 person objects, 108 PHP, 3 plain text cookies, 148 pluralization support, 149 POST requests, 102, 116 price, sum total, 31 principle of least knowledge, 5 priority property, 120, 122 production-ready apps, 66 project organization, 47, 67 Promise interface, 102 Promise proposal, 113 promises, 82 propagation, ascertaining full, 31 prototypal inheritance, 13 Provider API call, 145 R radio buttons, 16 Rails, 3, 12 realtime web apps, 164 Index | 181 recipe management applications, 77 Regex patterns, 95 relative links, 142 replace property, 120 request transformations, 106 requests, configuring, 103 require property, 120, 133 Requirejs, 67–74 reset buttons, 18 response interception, 115 response transformations, 106 RESTful resources, 81, 108–113 RESTful servers, 81 restrict property, 120, 122 rounding up/down, 37 routes adding with Yeoman, 66 alternatives to, 138 changing views with, 38–41 list template and, 91 rows, highlighting, 25 Run block, 143 S same origin policy, 125 sample application structure, 48 sanitize module, 150 Save buttons, 95 Scenario Runner, 56 scenario tests, 99 scope property, 120 Scope.$apply, 138 scopes $scope object, 13, 24 accessing from directives, 128–131 communicating between, 146 controller inheritance, 28 examining with Batarang, 60 publishing model data with, 28 screen flicker, 26, 113 script library, loading, 11 script tag, 90 search boxes, 161 security issues, 116–117, 150–152 selectedRow function, 26 sensitive information, 116 server authentication, 34 server-side communication, 101–117 asynchronous requests and, 113 over $http, 101–106, 171–174 response interception, 115 RESTful resources, 108–113 security issues, 116–117 unit testing, 107 server-side configuration, 141 servers, communicating with, 41 Service API call, 145 service dependency management, 62, 67 services, 34, 35, 79, 80–83 session cookies, 117 shopping cart example brief explanation, 6 discount application, 30 Simple optimization, 58 single-instance objects, 35 single-page applications, Angular vs. other apps, 2 singleton objects, 35 Smalltalk, 3 Socket.IO, 164–167 special headers, 104 spurious HTTP/XHR requests, 116 src attribute, 26 static resources, 49 styles, 24 T tabbed views, 123 tables, 21 TDD (Test-Driven Development), 53 Teams List app example, 157 template property, 120 templates and data binding, 14–33 basics of, 78 canonical vs. copy of, 122 client side, 2, 57 file location of, 48 for directives, 120, 123–125 model setting from, 28 working examples of, 89–95 writing as HTML, 5, 12 templateUrl property, 120, 125 testing scenario tests, 99 unit tests, 95, 107 with Yeoman, 66 text inputs, 16 182 | Index text, displaying/updating of, 15 then() functions, 82 third-party libraries, 37 throw operator, 27 time zones, 150 tokens, 117 transclude property, 120, 126 transformations, 106 transitive changes, 31 U UIs (User Interfaces) creating dynamic, 4 separating responsibilities in, 27 unauthorized transfers, 117 unit tests, 95–99 for $http service, 107 for app logic, 21 for ngResource, 112 in Karma, 71 Jasmine style, 54 Jasmine-style, 49 with monkey patches, 34 uppercase filter, 37 user input, validation of, 45, 94 username requirement, enforcing, 95 V validation tools, 53, 119 (see also form validation controls) variables, in data binding, 7 vendor folder, 48 View Controller, 86 views adding with Yeoman, 66 basics of, 12, 79 changing with routes and $location, 38–41 creation of, 12 exposing model data to, 28 working example of, 91 W watchAction, 29 watchFn, 29, 31 web development platforms, 50 web servers starting with ExpressJS, 51 starting with Yeoman, 51 WebSockets, 34 WebStorm development platform, 50 while loop, 27 window.location vs. $location, 137 Windows OS, and Yeoman, 48 workflow optimization, 64 X XHR, 34 xHTML naming format, 119 XML naming format, 119 XSRF, 42 XSRF (Cross-Site Request Forgery) attacks, 116 Y Yeoman, 64 overview of, 47 starting web servers in, 51 Index | 183 About the Authors Brad Green works at Google as an engineering manager. In addition to the AngularJS project, Brad also directs Accessibility and Support Engineering. Prior to Google, Brad worked on the early mobile web at AvantGo, founded and sold startups, and spent a few hard years toiling as a caterer. Brad’s first job out of school was as a lackey to Steve Jobs at NeXT Computer, writing demo software and designing Jobs’ slide presentations. Brad lives in Mountain View, CA, with his wife and two children. Shyam Seshadri is the owner and CEO of Fundoo Solutions, where he splits his time between working on innovative and exciting new products for the Indian market, and consulting about and running workshops on AngularJS. Prior to Fundoo Solutions, Shyam completed his MBA from the prestigious Indian School of Business in Hydera‐ bad. Shyam’s first job out of college was with Google, where he worked on multiple projects, including Google Feedback (AngularJS’s first customer!), and various internal tools and projects. Shyam currently operates from his office in Navi Mumbai, India. Colophon The animal on the cover of AngularJS is a thornback cowfish (Ostraciidae). This fish of many names—thornback, thornback cow, backspine cowfish, shortspined cowfish, blue-spotted cowfish—is usually found on rocky reefs or sandy slopes in a tangle of sponge and weeds in the Western Indo-Pacific region. They feed primarily on worms and other invertebrates. These boxfish can grow up to 15 centimeters long and anywhere between 3 to 50 meters wide. Members of the boxfish family are recognizable by the hexagonal pattern on their skin. Their bodies are shaped like a boxy triangle from which their fins, tail, eyes, and mouth protrude, allowing them to swim with a rowing motion. As they age, their shapes change from more rounded to more square-shaped, and their brighter colors dim. The thornback cowfish protects itself by secreting cationic surfactants through their skin, which is triggered by stress. The toxins, usually secreted in the form of a mucus, dissolve into the environment and irritate fish in the surrounding area. The cover image is from Johnson’s Natural History. The cover font is Adobe ITC Ga‐ ramond. The text font is Adobe Minion Pro; the heading font is Adobe Myriad Con‐ densed; and the code font is Dalton Maag’s Ubuntu Mono.