Contrasting the utilization of Angular $scope dependency with independent usage

Question

Contrasting the utilization of Angular $scope dependency with independent usage

As I delve into Angular, there's something that puzzles me. Being a newcomer to Angular, I recall a tutorial where they employed this syntax for applying properties to a controller's scope:

app.controller('someCtrl', function(){
        this.variable = "hey!";
});

Initially, everything was smooth as I started building my web app. However, when I attempted to add some socket.io interactivity with my node.js server, things took a turn. In search of tutorials on integrating them, I stumbled upon this alternative syntax:

app.controller('someCtrl', ['$scope', function($scope){
        $scope.variable = "hey!";
}]);

Feeling perplexed by the difference, I decided to dig deeper into Angular's resources on dependency injection and scopes. It turns out that this is the standard way of doing things, allowing interaction not just with $rootScope but also other elements necessary for controllers to communicate effectively. But still, I can't quite grasp the distinction between the two approaches. Could it be that the first one serves as a basic introduction to angular, easing newcomers into the realm of scopes and dependency injection?

Appreciate any insights you can provide.

javascript angularjs socket.io angularjs-scope

Answer 1

Answer №1

It is incredibly confusing and I really wish the Angular developers would stick to using just one method. The first option is more user-friendly for JavaScript developers, although it seems the documentation no longer mentions this:

In previous versions of Angular (pre 1.0 RC), you could use 'this' interchangeably with the $scope method, but that is no longer the case. While methods defined within the scope can use 'this' and $scope interchangeably (angular sets this to $scope), this does not apply elsewhere in your controller constructor.

In recent versions, the second syntax (injecting $scope via dependency injection) is more commonly used, despite being intimidating to newcomers due to the array in the function variable list (necessary for minification).

The situation becomes more complicated as 'this' reappears in a different form known as the "controller as" syntax:

HTML

<div ng-controller="MainController as main">  
  {{ main.someProp }}
</div>

JavaScript

app.controller('MainController', function () {  
  var model = this;
  model.someProp = 'Some value.'
});

Most likely, what you've come across is the "controller as" syntax which is gaining popularity over the second method involving dependency injection. You can identify it in HTML by looking for XxxController as yyyy.

Typically, working with 'this' all the time in your controller's functions can introduce bugs due to scoping issues in JavaScript. It's recommended to assign 'this' to a local variable right away and work with that variable (such as 'model' in my example), similar to how you would use '$scope'.

TL;DR: Adapt to using the "controller as" syntax for future compatibility, even though historically injecting $scope was considered best practice.

Answer 2

It is incredibly confusing and I really wish the Angular developers would stick to using just one method. The first option is more user-friendly for JavaScript developers, although it seems the documentation no longer mentions this:

In previous versions of Angular (pre 1.0 RC), you could use 'this' interchangeably with the $scope method, but that is no longer the case. While methods defined within the scope can use 'this' and $scope interchangeably (angular sets this to $scope), this does not apply elsewhere in your controller constructor.

In recent versions, the second syntax (injecting $scope via dependency injection) is more commonly used, despite being intimidating to newcomers due to the array in the function variable list (necessary for minification).

The situation becomes more complicated as 'this' reappears in a different form known as the "controller as" syntax:

HTML

<div ng-controller="MainController as main">  
  {{ main.someProp }}
</div>

JavaScript

app.controller('MainController', function () {  
  var model = this;
  model.someProp = 'Some value.'
});

Most likely, what you've come across is the "controller as" syntax which is gaining popularity over the second method involving dependency injection. You can identify it in HTML by looking for XxxController as yyyy.

Typically, working with 'this' all the time in your controller's functions can introduce bugs due to scoping issues in JavaScript. It's recommended to assign 'this' to a local variable right away and work with that variable (such as 'model' in my example), similar to how you would use '$scope'.

TL;DR: Adapt to using the "controller as" syntax for future compatibility, even though historically injecting $scope was considered best practice.

Answer 3

Answer №2

Essentially, to avoid issues with minification, it is recommended to inject the `$scope` directly as a dependency.

During minification, the variable `$scope` can be renamed to something like `e`, causing Angular to not recognize how to use `e` itself.

var app=angular.module("myApp",[]);app.controller("mainController",function(e){e.message="OH NO!"})

By injecting the dependency directly as shown, the `$scope` will retain its original name and Angular will function properly.

For more information, check out this article on Scotch.io

I trust this explanation has been beneficial.

Answer 4

Essentially, to avoid issues with minification, it is recommended to inject the `$scope` directly as a dependency.

During minification, the variable `$scope` can be renamed to something like `e`, causing Angular to not recognize how to use `e` itself.

var app=angular.module("myApp",[]);app.controller("mainController",function(e){e.message="OH NO!"})

By injecting the dependency directly as shown, the `$scope` will retain its original name and Angular will function properly.

For more information, check out this article on Scotch.io

I trust this explanation has been beneficial.

Contrasting the utilization of Angular $scope dependency with independent usage

Answer №1

Answer №2

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