node package manager


Universal dynamic module loader


Build Status Gitter Support

Universal dynamic module loader - loads ES6 modules, AMD, CommonJS and global scripts in the browser and NodeJS.

Built to the format ES6-specified loader API from ES6 Specification Draft Rev 27, Section 15, and will be updated to the WhatWG loader API as soon as it can be considered stable for implementation.

~19KB minified and gzipped, runs in IE8+ and NodeJS.

For discussion, join the Gitter Room.


Basic Use


<script src="system.js"></script>
  // set our baseURL reference path 
    baseURL: '/js'
  // loads /js/main.js 

The above will support loading all module formats, including ES Modules transpiled into the System.register format.

To load ES6 code with in-browser transpilation, configure one of the following transpiler plugins:

Promise Polyfill

SystemJS relies on Promise being present in the environment.

For the best performance in IE and older browsers, it is advisable to load a polyfill like Bluebird or es6-promise before SystemJS.

Otherwise, when Promise is not available, SystemJS will attempt to load the system-polyfills.js file located in the dist folder which contains the when.js Promise polyfill.


To load modules in NodeJS, install SystemJS with:

  npm install systemjs

If transpiling ES6, also install the transpiler plugin, following the instructions from the transpiler project page.

We can then load modules equivalently in NodeJS as we do in the browser:

var SystemJS = require('systemjs');
// loads './app.js' from the current directory 
SystemJS.import('./app.js').then(function(m) {

If you are using jspm as a package manager you will also need to load the generated configuration. The best way to do this in node is to get your System instance through jspm, which will automatically load your config correctly for you:

var Loader = require('jspm').Loader;
var SystemJS = new Loader();
SystemJS.import('lodash').then(function (_) {


Supported loader plugins:

Additional 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.