13-2 Implementing Features
Key Concepts
- Feature Modules
- Lazy Loading
- Shared Modules
- Core Modules
- Routing and Navigation
- Dependency Injection
- Component Communication
- State Management
- Forms and Validation
- HTTP Client
- Animations
- Internationalization
- Testing
1. Feature Modules
Feature modules in AngularJS are modules that encapsulate a specific feature or functionality of the application. They help in organizing the codebase and improving maintainability.
Example:
angular.module('userModule', [])
.controller('UserController', function($scope) {
$scope.users = [];
});
Imagine feature modules as separate rooms in a house, each dedicated to a specific function (feature) like a kitchen or a bedroom.
2. Lazy Loading
Lazy loading is a design pattern that loads components or modules only when they are needed. This improves the performance of the application by reducing the initial load time.
Example:
$stateProvider.state('profile', {
url: '/profile',
templateUrl: 'profile.html',
controller: 'ProfileController',
resolve: {
load: function($q, $timeout) {
var deferred = $q.defer();
$timeout(function() {
deferred.resolve();
}, 1000);
return deferred.promise;
}
}
});
Think of lazy loading as a library that only opens the book (loads the component) when you need to read it, rather than opening all books at once.
3. Shared Modules
Shared modules contain components, directives, and services that are used across multiple feature modules. They promote code reuse and maintainability.
Example:
angular.module('sharedModule', [])
.directive('myDirective', function() {
return {
restrict: 'E',
template: '<div>Shared Directive</div>'
};
});
Consider shared modules as a toolbox that contains tools (components, directives) used by different rooms (feature modules) in a house.
4. Core Modules
Core modules contain singleton services and components that are used throughout the application. They are typically loaded only once and are essential for the application's functionality.
Example:
angular.module('coreModule', [])
.service('AuthService', function() {
this.isAuthenticated = function() {
return true;
};
});
Think of core modules as the foundation of a house, providing essential services (utilities) that are used by all rooms (feature modules).
5. Routing and Navigation
Routing and navigation in AngularJS allow you to create single-page applications (SPAs) with multiple views. The ngRoute module provides routing and deeplinking services.
Example:
$routeProvider
.when('/home', {
templateUrl: 'home.html',
controller: 'HomeController'
})
.otherwise({
redirectTo: '/home'
});
Imagine routing and navigation as a tour guide that takes you (user) to different locations (views) within the same city (SPA) based on your request (URL).
6. Dependency Injection
Dependency Injection (DI) in AngularJS is a design pattern that allows you to inject dependencies into your components. It promotes modularity and testability.
Example:
angular.module('myApp', [])
.controller('MyController', function($scope, myService) {
$scope.data = myService.getData();
});
Consider DI as a chef assembling a dish. The chef (controller) uses ingredients (services) provided by the kitchen (DI container) to prepare the meal (application).
7. Component Communication
Component communication in AngularJS involves passing data and events between parent and child components. This can be done using bindings, services, and events.
Example:
<parent-component>
<child-component data="parentData"></child-component>
</parent-component>
Think of component communication as a conversation between family members. Each member (component) shares information (data) with others to coordinate activities.
8. State Management
State management in AngularJS involves managing the state of the application, including data and UI state. This can be done using services, factories, and observables.
Example:
angular.module('myApp', [])
.factory('StateService', function() {
var state = {
data: []
};
return {
getState: function() {
return state;
},
setState: function(newState) {
state = newState;
}
};
});
Consider state management as a memory bank that stores and retrieves information (state) about the application's current situation.
9. Forms and Validation
Forms and validation in AngularJS involve creating and validating user input forms. This includes handling form controls, validation rules, and error messages.
Example:
<form name="myForm" ng-submit="submitForm()">
<input type="text" name="username" ng-model="user.username" required>
<span ng-show="myForm.username.$error.required">Username is required</span>
<button type="submit">Submit</button>
</form>
Think of forms and validation as a checklist that ensures all required information (inputs) is provided correctly before proceeding.
10. HTTP Client
The HTTP client in AngularJS allows you to make HTTP requests to a server. This is essential for fetching data from APIs and interacting with backend services.
Example:
angular.module('myApp', [])
.controller('MyController', function($scope, $http) {
$http.get('/api/data')
.then(function(response) {
$scope.data = response.data;
});
});
Consider the HTTP client as a messenger that sends and receives messages (requests and responses) between the application and the server.
11. Animations
Animations in AngularJS allow you to add dynamic and interactive effects to your application. The ngAnimate module provides support for CSS and JavaScript animations.
Example:
angular.module('myApp', ['ngAnimate'])
.animation('.slide-animation', function() {
return {
enter: function(element, done) {
element.css('opacity', 0);
$(element).animate({opacity: 1}, 1000, done);
}
};
});
Think of animations as special effects in a movie. Each effect (animation) adds excitement and engagement to the scene (application).
12. Internationalization
Internationalization in AngularJS allows you to create multilingual applications. The ngLocale module provides support for different locales and languages.
Example:
angular.module('myApp', ['ngLocale'])
.config(function($translateProvider) {
$translateProvider.translations('en', {
'HELLO': 'Hello'
});
$translateProvider.translations('es', {
'HELLO': 'Hola'
});
$translateProvider.preferredLanguage('en');
});
Imagine internationalization as a translator that ensures your application speaks (displays content) in the user's language.
13. Testing
Testing in AngularJS involves writing unit tests with Jasmine and running them with Karma. This ensures your application is robust and free of bugs.
Example:
describe('Calculator', function() {
it('should add two numbers', function() {
expect(add(1, 2)).toBe(3);
});
});
Consider testing as quality control in a factory. Each product (component) is rigorously tested (unit tested) to ensure it meets the required standards (expected behavior).