ES6 Module Loader
ES6 Module Loader polyfill based on http://wiki.ecmascript.org/doku.php?id=harmony:module_loaders by Luke Hoban, Addy Osmani and Guy Bedford.
Not yet suitable for production use while the specification is still subject to change.
Download
Getting Started
Include the loader in the page:
<script src="path/to/es6-module-loader.js"></script>
Use the System (pre-configured Loader):
<script>
System.baseURL = '/lib';
System.import('js/test1', function (test1) {
console.log('js/test1.js loaded', test1);
});
</script>
where, test1 can contain module syntax:
test1.js:
export function tester() {
console.log('hello!');
}
Load multiple modules:
System.import(['js/test1', 'js/test2'], function(test1, test2) {
console.log('test1.js loaded', test1);
console.log('test2.js loaded', test2);
}, function(err) {
console.log('loading error');
});
Load a plain JavaScript file from a URL:
System.load('js/libs/jquery-1.7.1.js', function() {
var $ = System.global.jQuery;
console.log('jQuery loaded', $);
$('body').css({'background':'blue'});
});
Integration with Traceur
Include both Traceur and the ES6 module loader in the page:
<script src="path/to/traceur.js"></script>
<script src="path/to/es6-module-loader.js"></script>
Load an ES6 module (test.js):
export class MyClass {
foo() {
console.log('es6!');
}
}
Import the module:
<script>
System.load('test', function(test) {
new test.MyClass();
});
</script>
Creating a Custom Loader
Define a new module Loader instance:
var loader = new Loader({
global: window,
strict: false,
normalize: function (name, referer) {
return normalized(name, referer.name);
},
resolve: function (normalized, options) {
return '/' + normalized + '.js';
},
fetch: function (url, fulfill, reject, options) {
fulfill(source);
},
translate: function (source, options) {
return compile(source);
},
link: function (source, options) {
return {
imports: ['some', 'dependencies'],
execute: function(depA, depB) {
return new Module({
some: 'export'
});
}
};
}
});
The above hooks are all optional, using the default System hooks when not present.
For an overview of working with custom loaders, see Yehuda Katz's essay or the ES6 Module Specification.
Notes and roadmap
Syntax Parsing
The Esprima ES6 Harmony parser is being used to do parsing, loaded only when necessary.
The following module statements are currently supported:
import 'jquery';
import $ from 'jquery';
import { $ } from 'jquery';
import { $ as jQuery } from 'jquery';
export var x = 42;
export function foo() {};
export default var x = 42;
export default function foo() {};
export default = function foo() {};
export { encrypt };
export { decrypt as dec };
export { encrypt as en } from 'crypto';
export * from 'crypto';
NodeJS Support
For use in NodeJS, the Module
, Loader
and System
globals are provided as exports:
var System = require('es6-module-loader').System;
System.import('some-module', callback);
Tracuer support can also be used in NodeJS, allowing ES6 syntax in NodeJS:
require('es6-module-loader').traceur = require('traceur');
var System = require('es6-module-loader').System;
System.import('es6-file', function(module) {
module.classMethod();
});
Custom Esprima Location
To set a custom path to the Esprima Harmony parser, specify the data-esprima-src
attribute on the <script>
tag used to include the module loader.
Specification Notes
The polyfill is implemented exactly to the specification as closely as possible.
The only feature which is not possible to fully polyfill is the intrinsics functionality and sandboxing of the loader. Custom builtins and full global encapsulation is still provided.
The System normalization and resolution functions are not fully described by the specification, so some assumptions have been made which are listed here https://gist.github.com/guybedford/3712492cf0f629eed761.
To follow the current the specification changes, see https://github.com/ModuleLoader/es6-module-loader/issues?labels=specification&page=1&state=open.
Projects using us
- JSPM Loader is a RequireJS-style loader using our polyfill to load ES6, AMD, CommonJS and global modules
Contributing
In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using grunt.
Also, please don't edit files in the "dist" subdirectory as they are generated via grunt. You'll find source code in the "lib" subdirectory!
Release History
- 0.2.4 NodeJS support, relative normalization fixes, IE8 support
- 0.3.0 Traceur support, better error reporting, source maps support, normalization simplifications
License
Copyright (c) 2012 Luke Hoban, Addy Osmani, Guy Bedford
Licensed under the MIT license.