Dependency Injection (also called DI) is one of the best features of AngularJS. It is a software design pattern where objects are passed as dependencies rather than hard coding them within the component. It is useful for removing hard-coded dependencies and making dependencies configurable. To retrieve the required elements of the application that need to be configured when the module is loaded, the “config” operation uses Dependency Injection. It allows separating the concerns of different components in an application and provides a way to inject the dependent component into the client component. By using Dependency Injection, we can make components maintainable, reusable, and testable.

A simple case of dependency injection in AngularJS is shown below:

myApp.controller(‘myController’, function ($scope, $http, $location)
{
//logic
});
Here, a controller is declared with its dependencies.

AngularJS provides the following core components which can be injected into each other as dependencies:

Value
Factory
Service
Provider
Constant
In AngularJS, Dependency Injection (DI) is a design pattern that allows you to inject dependencies (such as services or objects) into a component or module rather than creating them within the component. This approach promotes the separation of concerns and makes components more modular, testable, and maintainable.
In the context of AngularJS, the framework’s injector is responsible for managing and injecting dependencies into components. When you define a component, controller, or service in AngularJS, you can declare its dependencies as parameters in the function or constructor. The AngularJS injector then provides the required dependencies when creating an instance of that component or service.

Here’s a simple example in AngularJS:

javascript

// Define a service
angular.module(‘myApp’).service(‘userService’, function() {
this.getUser = function() {
return { name: ‘John’, age: 30 };
};
});

// Define a controller with dependency injection
angular.module(‘myApp’).controller(‘UserController’, function($scope, userService) {
$scope.user = userService.getUser();
});

In this example, the UserController has a dependency on the userService, and AngularJS’s injector ensures that the userService is available when creating an instance of the UserController. Dependency Injection helps in managing the relationships between different components and makes it easier to replace or update dependencies without modifying the dependent components