Various concepts of AngularJS are discussed.
AngularJS and Javascript
AngularJS is a JavaScript framework. It can be added to an HTML page with a <script> tag. AngularJS extends HTML attributes with Directives, and binds data to HTML with Expressions. AngularJS is a JavaScript framework. It is a library written in JavaScript. AngularJS is distributed as a JavaScript file, and can be added to a web page with a script tag:
<script src=”https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js”></script>
AngularJS and HTML
AngularJS extends HTML with ng-directives. The ng-app directive defines an AngularJS application. The ng-model directive binds the value of HTML controls (input, select, textarea) to application data. The ng-bind directive binds application data to the HTML view.
Example
<!DOCTYPE html>
<html>
<script src=”https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js”></script>
<body>
<div ng-app=””>
<p>Name: <input type=”text” ng-model=”name”></p>
<p ng-bind=”name”></p>
</div>
</body>
</html>
Example explained:
AngularJS starts automatically when the web page has loaded. The ng-app directive tells AngularJS that the <div> element is the “owner” of an AngularJS application.
The ng-model directive binds the value of the input field to the application variable name. The ng-bind directive binds the innerHTML of the <p> element to the application variable name.
AngularJS Directives
AngularJS directives are HTML attributes with an ng prefix. The ng-init directive initializes AngularJS application variables.
Example
<div ng-app=”” ng-init=”firstName=’Demo'”>
<p>The name is <span ng-bind=”firstName”></span></p>
</div>
AngularJS Expressions
AngularJS expressions are written inside double braces: {{ expression }}. AngularJS will “output” data exactly where the expression is written:
Example
<!DOCTYPE html>
<html>
<script src=”https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js”></script>
<body>
<div ng-app=””>
<p>My first expression: {{ 5 + 5 }}</p>
</div>
</body>
</html>
AngularJS expressions bind AngularJS data to HTML the same way as the ng-bind directive.
Example
<!DOCTYPE html>
<html>
<script src=”https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js”></script>
<body>
<div ng-app=””>
<p>Name: <input type=”text” ng-model=”name”></p>
<p>{{name}}</p>
</div>
</body>
</html>
AngularJS Applications
AngularJS modules define AngularJS applications. AngularJS controllers control AngularJS applications. The ng-app directive defines the application, the ng-controller directive defines the controller.
Example
<div ng-app=”myApp” ng-controller=”myCtrl”>
First Name: <input type=”text” ng-model=”firstName”><br>
Last Name: <input type=”text” ng-model=”lastName”><br>
<br>
Full Name: {{firstName + ” ” + lastName}}
</div>
<script>
var app = angular.module(‘myApp’, []);
app.controller(‘myCtrl’, function($scope) {
$scope.firstName= “Demo”;
$scope.lastName= “User”;
});
</script>
AngularJS modules define applications:
AngularJS Module
var app = angular.module(‘myApp’, []);
AngularJS controllers control applications:
AngularJS Controller
app.controller(‘myCtrl’, function($scope) {
$scope.firstName= “Demo”;
$scope.lastName= “User”;
});
