systemjs

What is systemjs?

SystemJS is a dynamic module loader that can load ES modules, AMD, CommonJS, and global scripts in the browser and Node.js. It provides a way to load modules asynchronously and supports various module formats, making it a versatile tool for managing dependencies and module loading in JavaScript applications.

What are systemjs's main functionalities?

Loading ES Modules

SystemJS can dynamically import ES modules. The code sample demonstrates how to load an ES module asynchronously and handle the loaded module.

System.import('/path/to/module.js').then(function(module) {
  console.log(module);
});

Loading CommonJS Modules

SystemJS can also load CommonJS modules. The code sample shows how to load a CommonJS module asynchronously.

System.import('/path/to/commonjs-module.js').then(function(module) {
  console.log(module);
});

Loading AMD Modules

SystemJS supports loading AMD modules. The code sample demonstrates how to load an AMD module asynchronously.

System.import('/path/to/amd-module.js').then(function(module) {
  console.log(module);
});

Loading Global Scripts

SystemJS can load global scripts that do not export any modules. The code sample shows how to load a global script asynchronously.

System.import('/path/to/global-script.js').then(function() {
  console.log('Global script loaded');
});

Configuring SystemJS

SystemJS allows configuration for module loading. The code sample demonstrates how to configure the base URL, paths, and module mappings.

System.config({
  baseURL: '/base/url',
  paths: {
    'npm:': 'https://unpkg.com/'
  },
  map: {
    'jquery': 'npm:jquery@3.5.1/dist/jquery.js'
  }
});

Other packages similar to systemjs

requirejs

RequireJS is a JavaScript file and module loader. It is optimized for in-browser use, but it can be used in other JavaScript environments, such as Rhino and Node. Compared to SystemJS, RequireJS primarily focuses on AMD modules and does not support as many module formats.

webpack

Webpack is a module bundler that takes modules with dependencies and generates static assets representing those modules. Unlike SystemJS, which is a dynamic module loader, Webpack bundles modules at build time, which can result in better performance for production applications.

browserify

Browserify allows you to use Node.js-style require() to organize your browser code and load modules. It transforms Node.js modules into a format that can be used in the browser. Compared to SystemJS, Browserify focuses on CommonJS modules and does not support as many module formats.

es-module-loader

ES Module Loader is a polyfill for the ES Module Loader specification. It provides a way to load ES modules in environments that do not natively support them. Compared to SystemJS, ES Module Loader is more focused on ES modules and does not support other module formats.

README

SystemJS

Universal dynamic module loader - loads ES6 modules, AMD, CommonJS and global scripts in the browser and NodeJS. Works with both Traceur and Babel.

Designed as a collection of extensions to the ES6 module loader which can also be applied individually.

• Loads any module format with exact circular reference and binding support.
• Loads ES6 modules compiled into the System.register bundle format for production, maintaining circular references support.
• Supports RequireJS-style map, paths, bundles and global shims.
• Loader plugins allow loading assets through the module naming system such as CSS, JSON or images.

Designed to work with the ES6 Module Loader polyfill (9KB) for a combined total footprint of 16KB minified and gzipped.

Runs in IE8+ and NodeJS.

For discussion, see the Google Group.

For a list of guides and tools, see the community project page.

Documentation

• Basic Use
• Configuration Options
• Loader Configuration
• Map Configuration
• Meta Configuration
• Module Format Support
• Relative Dynamic Loading
• Versions Extension
• Production Workflows
• Creating Plugins
• Creating a Custom Module Format

Getting Started

Browser Use

Download es6-module-loader.js into the same folder as system.js.

Load SystemJS with a single script tag:

<script src="system.js"></script>

It will load es6-module-loader.js itself.

To load ES6, locate traceur.js in the same folder and it will be loaded when needed.

For use with Babel set:

<script>
  System.transpiler = 'babel';
</script>

Alternatively a custom path to Babel can also be set:

<script src="system.js" data-babel-src="path/to/babel.js"></script>

NodeJS Use

To load modules in NodeJS, install SystemJS with:

  npm install systemjs

We can then load modules equivalently to in the browser:

var System = require('systemjs');

/* 
 * Include
 *   System.transpiler = 'babel';
 * to use Babel instead of Traceur
 */

// loads './app.js' from the current directory
System.import('./app').then(function(m) {
  console.log(m);
});

If configuring baseURL for use in Windows, prepend file: i.e.

System.config({
 baseURL: 'file:' + path.resolve('../path')
});

Plugins

Plugins handle alternative loading scenarios, including loading assets such as CSS or images, and providing custom transpilation scenarios.

Supported Plugins:

• CSS System.import('my/file.css!')
• Image System.import('some/image.png!image')
• JSON System.import('some/data.json!').then(function(json){})
• Text System.import('some/text.txt!text').then(function(text) {})

Additional Plugins:

• CoffeeScript System.import('./test.coffee!')
• Jade
• JSX System.import('template.jsx!')
• Markdown System.import('app/some/project/README.md!').then(function(html) {})
• WebFont System.import('google Port Lligat Slab, Droid Sans !font')
• Ember Handlebars System.import('template.hbs!')

Plugins are loaded from the module name of the extension. To set them up, you'll most likely want to add map configuration. For example:

System.map['css'] = 'path/to/css/plugin';

Loading through plugin is indicated with ! at the end of the name:

System.import('file.css!');      // will use the "css" plugin, assumed from the extension
System.import('file.css!text');  // will use the "text" plugin, instead of checking the extension

Read the guide here on creating plugins.

Running the tests

To install the dependencies correctly, run bower install from the root of the repo, then open test/test.html in a browser with a local server or file access flags enabled.

License

MIT