AngularJS Introduction


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

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="http://ajax.googleapis.com/ajax/libs/angularjs/1.2.26/angular.min.js"></script>


AngularJS Extends 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.

AngularJS Example

<!DOCTYPE html>
<html>

<head>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.2.26/angular.min.js"></script>
</head>

<body>

<div ng-app="">
  <p>Name: <input type="text" ng-model="name"></p>
  <p ng-bind="name"></p>
</div>

</body>
</html>

Try it Yourself »

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

As you have already seen, AngularJS directives are HTML attributes with an ng prefix.

The ng-init directive initialize AngularJS application variables.

AngularJS Example

<div ng-app="" ng-init="firstName='John'">

<p>The name is <span ng-bind="firstName"></span></p>

</div>

Try it Yourself »
Note You can use data-ng-, instead of ng-, if you want to make your page HTML5 valid.

Alternatively with valid HTML5:

AngularJS Example

<div data-ng-app="" data-ng-init="firstName='John'">

<p>The name is <span data-ng-bind="firstName"></span></p>

</div>

Try it Yourself »

You will learn a lot more about directives later in this tutorial.


AngularJS Expressions

AngularJS expressions are written inside double braces: {{ expression }}.

AngularJS expressions bind data to HTML the same way as the ng-bind directive.

AngularJS will "output" data exactly where the expression is written.

AngularJS Example

<!DOCTYPE html>
<html>

<head>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.2.26/angular.min.js"></script>
</head>

<body>

<div ng-app="">
  <p>My first expression: {{ 5 + 5 }}</p>
</div>

</body>
</html>

Try it Yourself »

You will learn more about expressions later in this tutorial.


AngularJS Controllers

AngularJS applications are controlled by controllers.

The ng-controller directive defines the controller.

The controller code will execute when the page loads.

AngularJS Example

<div ng-app="" ng-controller="personController">

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>
function personController($scope) {
    $scope.firstName = "John";
    $scope.lastName = "Doe";
}
</script>

Try it Yourself »

You will learn a lot more about controllers later in this tutorial.



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