Should I avoid declaring global app variables in Angular?

Question

Should I avoid declaring global app variables in Angular?

After browsing several examples online, I have come across a common pattern in AngularJS code. The basic structure involves creating a new module using the angular.module() method and then retrieving it in other files within the same module.

var app = angular.module("ExampleApp", []);  // setter, creates a new module

app.controller(...

In subsequent files under the same Angular module, developers often retrieve the existing module like so:

var app = angular.module("ExampleApp");  // getter, retrieves the existing module

app.service(...

This practice introduces a global "app" variable that can be accessed across different files. However, there seem to be mixed opinions on whether it is preferable to skip the getter altogether and directly invoke app.service(....

While discarding the "getter" could raise concerns about best practices, some questions linger about the necessity of declaring the global variable at all. One suggestion is to encapsulate each file in an Immediately Invoked Function Expression (IIFE) to limit variable scope or eliminate the var app declaration and chain methods like .controller, .service, etc. directly onto angular.module().

I welcome any expert advice on this matter. Thank you in advance for your insights.

javascript angularjs

Answer 1

Answer №1

It is recommended to avoid using global variables as they can be mutated anywhere in the code, making it harder to maintain. A good practice is to create modules in a separate JavaScript file like this:

angular.module("ExampleApp", []);

Then you can access this module in other files without assigning it to a variable like this:

angular.module("ExampleApp")
    .service("MyService", function () {});

or

angular.module("ExampleApp")
    .component("MyComponent", {});

If you need to use variables, consider using functions instead like this:

(function () {
    var myController = function () {};

    myController.$inject = ["$scope"];

    angular.module("ExampleApp")
        .controller(myController);
})();

Using bundlers such as Webpack or Browserify is also a good practice as they automatically create scopes for each JavaScript file. This eliminates the need to use immediately invoked functions to hide variables from the global scope. For example:

var myController = require('./MyController.js');
var myApp = require('./ExampleApp.js');

myApp.controller(myController);

With webpack, the variables myController and myApp are not considered global variables, resulting in cleaner and simpler code.

Answer 2

It is recommended to avoid using global variables as they can be mutated anywhere in the code, making it harder to maintain. A good practice is to create modules in a separate JavaScript file like this:

angular.module("ExampleApp", []);

Then you can access this module in other files without assigning it to a variable like this:

angular.module("ExampleApp")
    .service("MyService", function () {});

or

angular.module("ExampleApp")
    .component("MyComponent", {});

If you need to use variables, consider using functions instead like this:

(function () {
    var myController = function () {};

    myController.$inject = ["$scope"];

    angular.module("ExampleApp")
        .controller(myController);
})();

Using bundlers such as Webpack or Browserify is also a good practice as they automatically create scopes for each JavaScript file. This eliminates the need to use immediately invoked functions to hide variables from the global scope. For example:

var myController = require('./MyController.js');
var myApp = require('./ExampleApp.js');

myApp.controller(myController);

With webpack, the variables myController and myApp are not considered global variables, resulting in cleaner and simpler code.

Answer 3

Answer №2

Whether or not to use global variables depends on how they are utilized. While sometimes it may be necessary to access variables globally, it is generally recommended to avoid them in order to prevent conflicts and potential issues. This is why, when developing Angular modules, developers often utilize self-invoking functions to limit access to global values.

To put it simply, if your project is not overly complex, using global variables may be acceptable. However, in cases of more intricate problems where multiple frameworks may be involved, it is best to steer clear of global variables. Using global variables in such scenarios can lead to conflicts with framework variables, resulting in hard-to-troubleshoot problems that may leave you scratching your head.

Answer 4

Whether or not to use global variables depends on how they are utilized. While sometimes it may be necessary to access variables globally, it is generally recommended to avoid them in order to prevent conflicts and potential issues. This is why, when developing Angular modules, developers often utilize self-invoking functions to limit access to global values.

To put it simply, if your project is not overly complex, using global variables may be acceptable. However, in cases of more intricate problems where multiple frameworks may be involved, it is best to steer clear of global variables. Using global variables in such scenarios can lead to conflicts with framework variables, resulting in hard-to-troubleshoot problems that may leave you scratching your head.

Should I avoid declaring global app variables in Angular?

Answer №1

Answer №2

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