---
title: "What is $rootScope in AngularJS?"  
description: "What is $rootScope in AngularJS?"  
author: "Ashutosh Patel"  
published: 2024-06-20  
updated: 2024-06-20  
canonical: https://www.mindstick.com/interview/33922/what-is-rootscope-in-angularjs  
category: "angular js"  
tags: ["javascript", "angular js", "angularjs service"]  
reading_time: 3 minutes  

---

# What is $rootScope in AngularJS?

#### $rootScope in AngularJS

In AngularJS, `$rootScope` is the parent scope created by the AngularJS framework itself. It sits at the top of the scope hierarchy for an AngularJS application.

**What is $rootScope in AngularJS?**\
$rootScope is the biggest scope in AngularJS applications, it acts as the parent scope for all other scopes.

**How does $rootScope differ from conventional scopes?**\
$rootScope is global and accessible throughout the application, whereas regular scopes are limited to their controllers or directives.

**What are the common expressions for $rootScope?**\
Sharing global data, defining global services, and using an event system ($emit, $broadcast, $on) for communication between parties.

**How does $rootScope facilitate component communication?**\
It provides $emit, $broadcast, and $on methods for triggering and listening for events in different parts of the application.

**Best practices when using $rootScope?**\
Use the global namespace sparingly to avoid clutter, prioritize tasks for data sharing, and focus on business specifications for broad events.

## Example-

```javascript
angular.module('myApp', [])
 .run(function($rootScope) {
   $rootScope.globalVar = 'Hello World'; // defining a global variable
   $rootScope.$on('someEvent', function(event, data) {
     console.log('Event received on $rootScope:', data);
   });
 })
 .controller('MyController', function($scope, $rootScope) {
   $scope.localVar = 'Local Variable'; // local to this controller's scope
   $rootScope.$broadcast('someEvent', 'Broadcasting data'); // broadcasting an event
 });
```

## In the example above

The `globalVar` defined in `$rootScope` can be accessed by any controller or directive in the application.\
$rootScope.$on('someEvent', ...) Listens for events sent from any part of the application.\
$rootScope.$broadcast('someEvent', ...) Creates an event that `$rootScope.$on` or **$scope.$on** can catch in child scopes.

**Also, Read:** [Explain the concept of "ng-repeat" in AngularJS](https://www.mindstick.com/interview/33921/explain-the-concept-of-ng-repeat-in-angularjs)

## Answers

### Answer by Ashutosh Patel

#### $rootScope in AngularJS

In AngularJS, `$rootScope` is the parent scope created by the AngularJS framework itself. It sits at the top of the scope hierarchy for an AngularJS application.

**What is $rootScope in AngularJS?**\
$rootScope is the biggest scope in AngularJS applications, it acts as the parent scope for all other scopes.

**How does $rootScope differ from conventional scopes?**\
$rootScope is global and accessible throughout the application, whereas regular scopes are limited to their controllers or directives.

**What are the common expressions for $rootScope?**\
Sharing global data, defining global services, and using an event system ($emit, $broadcast, $on) for communication between parties.

**How does $rootScope facilitate component communication?**\
It provides $emit, $broadcast, and $on methods for triggering and listening for events in different parts of the application.

**Best practices when using $rootScope?**\
Use the global namespace sparingly to avoid clutter, prioritize tasks for data sharing, and focus on business specifications for broad events.

## Example-

```javascript
angular.module('myApp', [])
 .run(function($rootScope) {
   $rootScope.globalVar = 'Hello World'; // defining a global variable
   $rootScope.$on('someEvent', function(event, data) {
     console.log('Event received on $rootScope:', data);
   });
 })
 .controller('MyController', function($scope, $rootScope) {
   $scope.localVar = 'Local Variable'; // local to this controller's scope
   $rootScope.$broadcast('someEvent', 'Broadcasting data'); // broadcasting an event
 });
```

## In the example above

The `globalVar` defined in `$rootScope` can be accessed by any controller or directive in the application.\
$rootScope.$on('someEvent', ...) Listens for events sent from any part of the application.\
$rootScope.$broadcast('someEvent', ...) Creates an event that `$rootScope.$on` or **$scope.$on** can catch in child scopes.

**Also, Read:** [Explain the concept of "ng-repeat" in AngularJS](https://www.mindstick.com/interview/33921/explain-the-concept-of-ng-repeat-in-angularjs)


---

Original Source: https://www.mindstick.com/interview/33922/what-is-rootscope-in-angularjs

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