MCQ

Angular MCQ

next → ← prev

AngularJS Scope

The scope is the binding part between the HTML (view) and the JavaScript (controller).

A scope is an object with available properties and methods.

The scope is available for both View and Controller.

When you create a controller in AngularJS, you pass the $scope object as an argument:

Example

Properties made in the controller can be referenced in the view:

<div ng-app="myApp" ng-controller="myCtrl">
<h1>{{carname}}</h1>
</div>
<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
  $scope.carname = "Volvo";
});
</script>

When adding properties to the $scope object in the controller, the view (HTML) gets access to these properties.

In the view, you do not use the prefix $scope, and you refer to a property name, like {{carname}}.

Understanding the Scope

If we consider including an AngularJS application:

Controller, which is a JavaScript function that creates/changes/deletes/controls data.

Then there is the scope model.

A scope is a JavaScript object with properties and methods available to both the view and the controller.

Example

If you make changes in the view, the model and the controller will be updated:

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

<input ng-model="name">

<h1>My name is {{name}}</h1>

</div>

<script>
var app = angular.module('myApp', []);

app.controller('myCtrl', function($scope) {
  $scope.name = "John Doe";
});

</script>

The two examples above only have one scope, so knowing your scope isn't a problem, but the HTML DOM may contain sections that only have access to certain scopes for larger applications.

Example

When working with the ng-repeat directive, each iteration has access to the current iteration object:

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

<ul>
  <li ng-repeat="x in names">{{x}}</li>
</ul>

</div>

<script>
var app = angular.module('myApp', []);

app.controller('myCtrl', function($scope) {
  $scope.names = ["Emil", "Tobias", "Linus"];
});

</script>

Each <li> element has access to the current iteration object, in this case, a string, which is referenced using x.

root scope

Each <li> element has access to the current iteration object, in this case, a string, which is referenced using x.

Root scope

All applications have a $rootScope, the scope created on the HTML element containing the ng-app directive.

RootScope is available throughout the application.

If a variable has the same name in both the current scope and the rootScope, the application uses the one in the current scope.

Example

A variable named "color" exists in both the controller's scope and the rootScope:

<body ng-app="myApp">

<p>The rootScope's favorite color:</p>
<h1>{{color}}</h1>

<div ng-controller="myCtrl">
  <p>The scope of the controller's favorite color:</p>
  <h1>{{color}}</h1>
</div>

<p>The rootScope's favorite color is still:</p>
<h1>{{color}}</h1>

<script>
var app = angular.module('myApp', []);
app.run(function($rootScope) {
  $rootScope.color = 'blue';
});
app.controller('myCtrl', function($scope) {
  $scope.color = "red";
});

Next Topic#

← prev next →