Expressions are used to bind application data to html. Expressions are written inside double braces like {{ expression}}. Expressions behaves in same way as ng-bind directives. AngularJS application expressions are pure javascript expressions and outputs the data where they are used.

Using numbers

<p>Expense on Books : {{cost * quantity}} Rs</p>

Using strings

<p>Hello {{student.firstname + ” ” + student.lastname}}!</p>

Using object

<p>Roll No: {{student.rollno}}</p>

Using array

<p>Marks(Math): {{marks[3]}}</p>

Example

Following example will showcase all the above mentioned expressions.

testAngularJS.htm

<html>

<head>

<title>AngularJS Expressions</title>

</head>

<body>

<h1>Sample Application</h1>

<div ng-app = “” ng-init = “quantity = 1;cost = 30;

student = {firstname:’Mahesh’,lastname:’Parashar’,rollno:101};

marks = [80,90,75,73,60]”>

<p>Hello {{student.firstname + ” ” + student.lastname}}!</p>

<p>Expense on Books : {{cost * quantity}} Rs</p>

<p>Roll No: {{student.rollno}}</p>

<p>Marks(Math): {{marks[3]}}</p>

</div>

</script>

</body>

</html>

Output

Open textAngularJS.htm in a web browser. See the result.

AngularJS – Controllers

AngularJS application mainly relies on controllers to control the flow of data in the application. A controller is defined using ng-controller directive. A controller is a JavaScript object containing attributes/properties and functions. Each controller accepts $scope as a parameter which refers to the application/module that controller is to control.

…

</div>

Here we’ve declared a controller studentController using ng-controller directive. As a next step we’ll define the studentController as follows −

function studentController($scope) {

$scope.student = {

firstName: “Mahesh”,

lastName: “Parashar”,

fullName: function() {

var studentObject;

studentObject = $scope.student;

return studentObject.firstName + ” ” + studentObject.lastName;

}

};

}

</script>

studentController defined as a JavaScript object with $scope as argument.
$scope refers to application which is to use the studentController object.
$scope.student is property of studentController object.
firstName and lastName are two properties of $scope.student object. We’ve passed the default values to them.
fullName is the function of $scope.student object whose task is to return the combined name.
In fullName function we’re getting the student object and then return the combined name.
As a note, we can also define the controller object in separate JS file and refer that file in the html page.

Now we can use studentController’s student property using ng-model or using expressions as follows.

Enter first name: <input type = “text” ng-model = “student.firstName”><br>

Enter last name: <input type = “text” ng-model = “student.lastName”><br>

<br>

You are entering: {{student.fullName()}}

We’ve bounded student.firstName and student.lastname to two input boxes.
We’ve bounded student.fullName() to HTML.
Now whenever you type anything in first name and last name input boxes, you can see the full name getting updated automatically.

Example

Following example will showcase use of controller.

testAngularJS.htm

<html>

<head>

<title>Angular JS Controller</title>

</script>

</head>

<body>

<h2>AngularJS Sample Application</h2>

Enter first name: <input type = “text” ng-model = “student.firstName”><br>

<br>

Enter last name: <input type = “text” ng-model = “student.lastName”><br>

<br>

You are entering: {{student.fullName()}}

</div>

var mainApp = angular.module(“mainApp”, []);

mainApp.controller(‘studentController’, function($scope) {

$scope.student = {

firstName: “Mahesh”,

lastName: “Parashar”,

fullName: function() {

var studentObject;

studentObject = $scope.student;

return studentObject.firstName + ” ” + studentObject.lastName;

}

};

});

</script>

</body>

</html>

Output

Open textAngularJS.htm in a web browser. See the result.

So, this brings us to the end of blog. This Tecklearn ‘Expressions and Controllers in Angular JS’ blog helps you with commonly asked questions if you are looking out for a job in Angular JS and Front-End Development. If you wish to learn Angular JS and build a career in Front-End Development domain, then check out our interactive, Angular JS Training that comes with 24*7 support to guide you throughout your learning period. Please find the link for course details:

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Building blocks of Angular
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Angular CLI
Angular CLI commands
Angular Modules

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Working of Angular Applications
Angular App Bootstrapping
Angular Components
Creating A Component Through Angular CLI
Ways to specify selectors
Template and styles
Installing bootstrap to design application
Data Binding
Types of Data Binding
Component Interaction using @Input and @Output decorator
Angular Animations

TypeScript

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Need of TypeScript
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Nodemon for monitoring changes
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Angular Directives
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Structural Directives
Attribute Directives
Custom Directives
Pipes
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Pipe Transform Interface & Transform Function
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Angular service
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Hierarchical Injector
Injecting A Service into Another Service
Observables
RxJS Library
Angular’s Interaction with Backend
Parts of an Http Request
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Forms in Angular
What are their functions
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Various Types of Forms
What is Angular Validation and Model driven approach

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Angular Routing
Angular Routing benefits and features
Building a single page application and updating it dynamically with Angular Routing
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Router Lifecycle Hooks and Child Routes

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What is Authentication?
Authentication and authorization
Types of Authentication
Where to store tokens?
JSON Web Tokens (JWT)
Authentication in Angular application
Security threats in web application

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Testing of Angular applications
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