RequireJS: Getting Started

Modular programming helps to divide the application code based on the module. These programming style helps to manage as well develop the application easily. Requirejs is lightweight framework used in javascript to develop applications using the modular programming.

RequireJS

RequireJS is lightweight javascript framework which enables AMD(Asynchronous Module Loader). RequireJS helps to load javascript file and modules asynchronously. Apart from using in browser , it’s also be used alongside in Node projects.

Why RequireJS?

It’s lightweight, scalable, comes with an excellent optimising tool. Apart from these the use of  RequireJS comes handy when you need to divide and load javascript files and modules whenever they need.

Suppose you had an application which have a home page, employees, and projects module. And had 3 javascript files like home.js, employees.js and projects.js. Normally in single page application you need to load these files when the page loads. Like

<script src="home.js"></script>
<script src="employees.js"></script>
<script src="projects.js"></script>

Suppose you need a framework like jquery datatables for employees. You will have load the frameworks also in the first load. If the user go to projects, the page will load entire js files .

Here the comes the requirejs for the rescue. What requireJs do is, it will load only selected files for the site. Suppose the user is in home page , it will not load the employee.js and projects.js and also the datatable framework. It increases the performance the speed of the site.

Prerequisites

1. Node
2. gulp
3. Bower

Source Code

https://github.com/harilal/blog-require

Installation

1. Clone the repo https://github.com/harilal/blog-require.git
2. Run the command inside blog-require npm install
3. Next run the command bower install  to install front end dependencies
4. gulp serve to run the server

Getting started

The application files are inside the dev folder. Open the index.html and go to the end of the file . You could see a

<script data-main="app" src="bower_components/requirejs/require.js"></script>

It loads the app.js file. In require the extension will not be used. So instead of app.js it will only say “app”. app.js is the entry point to the application Next open the app.js file.

define(['config'], function(config) {
 "use strict";
});

Here in we only loading the config file. Note that we are not using .js extension. Inside the function you will get an object of the loaded module. Lets look in to config.js.

requirejs.config({
    paths: {
        jquery: 'bower_components/jquery/dist/jquery.min',
        page: 'bower_components/page/page',
        text : 'bower_components/requirejs-text/text',
        underscore : 'bower_components/underscore/underscore-min'
    },
});

Here we are configuring the requirejs application. In path you could specify the modules you need to load. Later we could use the names instead of the full path when we load more modules. It’s just specifying the libraries we need

Note: When we load modules using RequireJS, it’s means we need that module in the application. It’s a required dependency. So if the module is not available it will throw an error and stops execution.

We will continue to add modules and check how it’s loaded in next post.