What is RequireJs and how to use it

RequireJS is a basic loader, which is used to loads the JavaScript files, it is a framework to manage dependencies between JavaScript files, and in modular programming, all the functionality divides in different modules, so RequireJs is a best tool to assemble different JavaScript files from different modules by which it helps to improve speed and quality of your code.

Why RequireJS

There are some reasons:

  •  In a large application a lot of JavaScript files are needed, and each script tag needs a request.
  •  You have to put them in a same order in which they are called, i.e. File which is dependent on other should be loaded after the dependent ones.

How to use

You can Downalod the file.

Take an example path of your JavaScript files:

|-scripts
	|--main.js
	|--require.js
	|--example.js

Now you just need to add a <script> tag in your html file to include Require.js file.

<script data-main="scripts/main" src="scripts/require.js"></script>

You can place this script tag at the head or at the bottom of the phtml file.

Here main.js is the main JavaScript file of my application.

In above <script> tag by the data-main attribute require.js will start initialization of files.(path of the folder/file name).
data-main is uses when you have only single entry point, if you have multiple entry points then you can include it by html also.

Now in main.js we have following code:

requirejs([
   "example"
], function(example) {
   //you code stuff is here
   //example.callFunction();
});

In RequireJS all the code is written under requirejs() or define() functions.

Here, It searched “example.js” in the same folder and take example as an object of the example.js file to call the functions of the example.js.

You can also include files from different folder’s.

Advantages of RequireJs

  • Lazy loading
  • Reduce code Complexity in large application
  • Assembly of different splited file at compile time
  • Less HTTP requests
  • No need to define them in some proper order

Hope this blog will help you to understand the basics of RequireJs.

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Comments (2)

Add Your Comment

  • sunanda
    The following fails. error https://requirejs.org/docs/errors.html#scripterror
    https://requirejs.org/docs/errors.html#scripterror

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    function save_content_to_file(){
    require([“r-script”]);

    • ashutosh srivastava
      you need to create the main.js file where you have to define the base url and paths for the above example like this:
      requirejs.config({
      baseUrl: ‘../scripts’,
      paths: {
      app: ‘../scripts’
      }
      });
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