About AMD modules and RequireJS

Overview

This topic discusses JavaScript modules and describes the role which RequireJS plays in Magento.

Magento uses AMD (asynchronous module definition) approach for JavaScript modules loading. Namely, Magento uses RequireJS and its standard syntax.

RequireJS configuration location

As Magento has a modular architecture we have an ability to define requirejs-config.js for each module, separately for each area: frontend or admin. (Or base if it is same for both, frontend and admin).

Following is the conventional location of requirejs-config.js (RequireJS configuration file):

• For modules: <Module_dir>/view/<area>/requirejs-config.js
• For themes: <theme_dir>/requirejs-config.js

RequireJS configuration file

requirejs-config.js is a valid JavaScript file. It should define the config variable, which is a configuration variable.

Example of usages

Lets look at an example, the Catalog module. In the <Magento_Catalog_module_dir>/view/base/requirejs-config.js file we see the configuration variable:

var config = {
    map: {
        '*': {
            categoryForm:       'Magento_Catalog/catalog/category/form',
            newCategoryDialog:  'Magento_Catalog/js/new-category-dialog',
            categoryTree:       'Magento_Catalog/js/category-tree',
            productGallery:     'Magento_Catalog/js/product-gallery',
            baseImage:          'Magento_Catalog/catalog/base-image-uploader',
            productAttributes:  'Magento_Catalog/catalog/product-attributes'
        }
    },
    deps: [
        'Magento_Catalog/catalog/product'
    ]
};

The config variable contains properties with the map and deps keys. These properties are equivalent to the native RequireJS properties. For example, in this case the map property contains an object with the keys that are aliases to files and values that are real paths to files.

For a particular area, all modules and themes requirejs-config.js files are merged into a single file. This file is written to the pub/static/requirejs directory. This occurs during the first launch of Magento in develop or default mode or during static files generation using the bin/magento setup:static-content:deploy console command.

The merged configuration will be loaded on the page right after require.js and will be used by require() and define() functions.

Example of how aliases can be used. Open a browser console on any Magento page and type:

    require(['productGallery']); // load the module on the page
    var gallery1 = require('productGallery');
    var gallery2 = require('Magento_Catalog/js/product-gallery');
    console.log(gallery1); // it does not return a simple type
    console.log(gallery1 === gallery2); // they are the same

Tip: One more way that you can use require object is to retrieve a current configuration during runtime. Just type in a browser console:

require.s.contexts._.config;