Angular JS - understanding the use of parameters in the module.controller function

Question

Angular JS - understanding the use of parameters in the module.controller function

As a newcomer to Angular JS, I came across a tutorial that outlines the process of creating a controller in the following way:

angular.module('app', [])
  .controller('TodoController', ['$scope', function ($scope) {
    $scope.todos = [
      { title: 'Learn Javascript', completed: true },
      { title: 'Learn Angular.js', completed: false },
      { title: 'Love this tutorial', completed: true },
      { title: 'Learn Javascript design patterns', completed: false },
      { title: 'Build Node.js backend', completed: false },
    ];
  }]);

I am eager to grasp the meaning and significance of each parameter involved:

'TodoController'
array
- '$scope'
- function

While I understand that the first parameter denotes the name of the controller and the last one signifies the TodoController constructor, I am unsure about '$scope'. Is it a variable name to be used in HTML or a method name?

Moreover, I am curious to know if it's possible to include more parameters in the array.

My attempts to find comprehensive documentation in Angular's official resources have been unfruitful, as the lack of specifics on methods is quite frustrating. Even searching through the class code has not yielded much more insight.

javascript angularjs angular-controller angular-module

Answer 1

Answer №1

Within the array, the input arguments (String) represent the dependencies to be injected in the specified order, excluding the last argument which is reserved for the constructor. These dependencies will be passed in the same order during the implementation of the controller (i.e. the constructor).

$scope is an object that maintains the connection with the view, and its contents are accessible in both the view and controller. It is generated by the $new method of the $rootScope (and then the hierarchy) whenever it is injected into a new controller that requires a new instance to be created.

Answer 2

Within the array, the input arguments (String) represent the dependencies to be injected in the specified order, excluding the last argument which is reserved for the constructor. These dependencies will be passed in the same order during the implementation of the controller (i.e. the constructor).

$scope is an object that maintains the connection with the view, and its contents are accessible in both the view and controller. It is generated by the $new method of the $rootScope (and then the hierarchy) whenever it is injected into a new controller that requires a new instance to be created.

Answer 3

Answer №2

Using an array of strings along with a function as the second argument is crucial for implementing dependency injection.

angular.controller('TaskController', ['$scope', function ($scope) { ... }])

By using this method, even if your code is minified, Angular will still be able to correctly inject the necessary dependencies as the strings act as a reference.

After minification, the above code may look like this:

angular.controller("TaskController",["$scope",function(o){...}]);

And Angular's dependency injection algorithm will still function properly for this minified code.

PS. The use of an array is optional, you can also just pass a plain function for dependency injection.

Answer 4

Using an array of strings along with a function as the second argument is crucial for implementing dependency injection.

angular.controller('TaskController', ['$scope', function ($scope) { ... }])

By using this method, even if your code is minified, Angular will still be able to correctly inject the necessary dependencies as the strings act as a reference.

After minification, the above code may look like this:

angular.controller("TaskController",["$scope",function(o){...}]);

And Angular's dependency injection algorithm will still function properly for this minified code.

PS. The use of an array is optional, you can also just pass a plain function for dependency injection.

Answer 5

Answer №3

Absolutely. Your understanding is spot on.

The first parameter identifies the controller name, while the second one represents an array. The last element in the array will be the controller function, and the other elements are the dependencies. This approach is known as Inline Array Annotation.

You have the option to create the controller without passing an array, unless you plan on minifying your code (Implicit Annotation).

Important Note: Be cautious when minifying your code, as your service names may get changed and potentially disrupt your application.

Please review the three methods for creating controllers or services by visiting https://docs.angularjs.org/guide/di

Answer 6

Absolutely. Your understanding is spot on.

The first parameter identifies the controller name, while the second one represents an array. The last element in the array will be the controller function, and the other elements are the dependencies. This approach is known as Inline Array Annotation.

You have the option to create the controller without passing an array, unless you plan on minifying your code (Implicit Annotation).

Important Note: Be cautious when minifying your code, as your service names may get changed and potentially disrupt your application.

Please review the three methods for creating controllers or services by visiting https://docs.angularjs.org/guide/di

Angular JS - understanding the use of parameters in the module.controller function

Answer №1

Answer №2

Answer №3

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