Wednesday 25 July 2018

AngularJS Controllers

A Controller takes the data from the View, processes the data, and then sends that data across to the view which is displayed to the end user. It maintains the application data and behavior using $scope object. 
It is used to control the data of AngularJS applications. A controller is defined using ng-controller directive. A controller is a JavaScript object containing attributes/properties and functions

Example 1:
<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script>
<body>
<div ng-app="myApp" ng-controller="myCtrl">
<h1>{{name}}</h1>
</div>
<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
    $scope.name = "suryosnata";
});
</script>
</body>
</html>

Example 2:
<!DOCTYPE html>
<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script>
<body>

<div ng-app="myApp" ng-controller="myCtrl">
 <p>Enter two number:</p>
<p>a value: <input type="number" ng-model="a"></p>
<p>b value: <input type="number" ng-model="b"></p>
<p>{{(a+b)}}</p>
</div>
<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
    $scope.a= 10;
    $scope.b= 15;
});
</script>
</body>
</html>

Imp Points:
The AngularJS application is defined by  ng-app="myApp". The application runs inside the <div>.
The ng-controller="myCtrl" attribute is an AngularJS directive. It defines a controller.
The myCtrl function is a JavaScript function.
AngularJS will invoke the controller with a $scope object.
In AngularJS, $scope is the application object (the owner of application variables and functions).
The controller creates two properties (variables) in the scope (a and b).
The ng-model directives bind the input fields to the controller properties (a and b).

Example 3:
<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script>
<body>
<div ng-app="myApp" ng-controller="myCtrl">
<ul>
    <li ng-repeat="y in fruits">{{y}}</li>
</ul>
</div>
<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
    $scope.fruits = ["apple", "orange", "mango"];
});
</script>

Controllers In External Files

 Example 4:
<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script>
<body>

<div ng-app="myApp" ng-controller="myCtrl">

<ul>
  <li ng-repeat="x in stud">
    {{ x.age+ ', ' + x.name }}
  </li>
</ul>
</div>
<script src="demoController.js"></script>
</body>
</html>
demoController.js
angular.module('myApp', []).controller('myCtrl', function($scope) {
    $scope.stud = [
        {age:'26',name:'suryosnata'},
        {age:'10',name:'khusi'},
        {age:'25',name:'hemant'}
    ];
});

Controller Methods

A controller can also have methods (variables as functions):
Example 5:
<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script>
<body>
<div ng-app="myApp" ng-controller="demoCtrl">
First Name: <input type="text" ng-model="firstName"><br>
Last Name: <input type="text" ng-model="lastName"><br>
<br>
Full Name: {{fullName()}}
</div>

<script>
var app = angular.module('myApp', []);
app.controller('demoCtrl', function($scope) {
    $scope.firstName = "suryosnata";
    $scope.lastName = "behera";
    $scope.fullName = function() {
        return $scope.firstName + " " + $scope.lastName;
    };
});
</script>

</body>
</html>

Example 6:
<!DOCTYPE html>
<html>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script>
<body>

<div ng-app="myApp" ng-controller="demoCtrl">

First Name: <input type="text" ng-model="firstName"><br>
Last Name: <input type="text" ng-model="lastName"><br>
<br>
Full Name: {{fullName()}}
</div>

<script src="demoController.js"></script>

</body>
</html>
demoController.js
angular.module('myApp', []);
app.controller('demoCtrl', function($scope) {
    $scope.firstName = "suryosnata";
    $scope.lastName = "behera";
    $scope.fullName = function() {
        return $scope.firstName + " " + $scope.lastName;
    };
});

Output:
First Name: 
Last Name: 


Full Name: suryosnata behera

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