Understanding AngularJS Bootstrap Process

29 dec. 2023

Beginner

29,5K Views

2 min read

Angular initializes automatically upon DOMContentLoaded event or when the angular.js script is downloaded to the browser and the document.readyState is set to complete. At this point AngularJS looks for the ng-app directive which is the root of angular app compilation and tells about AngularJS part within DOM. When the ng-app directive is found then Angular will:

Load the module associated with the directive.
Create the application injector.
Compile the DOM starting from the ng-app root element.

This process is called auto-bootstrapping.

<html>
<body ng-app="myApp">
 <div ng-controller="Ctrl">
 Hello {{msg}}!
 </div>

 <script src="lib/angular.js"></script>
 <script>
 var app = angular.module('myApp', []);
 app.controller('Ctrl', function ($scope) {
 $scope.msg = 'World';
 });
 </script>
</body>
</html>

Manual Bootstrap Process

You can manually initialized your angular app by using angular.bootstrap() function. This function takes the modules as parameters and should be called within angular.element(document).ready() function. The angular.element(document).ready() function is fired when the DOM is ready for manipulation.

<html>
<body>
 <div ng-controller="Ctrl">
 Hello {{msg}}!
 </div>
 <script src="lib/angular.js"></script>

 <script>
 var app = angular.module('myApp', []);
 app.controller('Ctrl', function ($scope) {
 $scope.msg = 'World';
 });

 //manual bootstrap process
 angular.element(document).ready(function () {
 angular.bootstrap(document, ['myApp']);
 });
 </script>
</body>
</html>

Note

You should not use the ng-app directive when manually bootstrapping your app.
You should not mix up the automatic and manual way of bootstrapping your app.
Define modules, controller, services etc. before manually bootstrapping your app as defined in above example.

What do you think?

I hope you will enjoy the AngularJS bootstrap process while developing your app with AngularJS. I would like to have feedback from my blog readers. Your valuable feedback, question, or comments about this article are always welcome. If you're eager to delve deeper into AngularJS and enhance your understanding of its bootstrap process and beyond, consider exploring our comprehensive Angular Training program.