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.
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'
}
});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 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 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 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.
For upgrading to SystemJS 0.17-0.19, see the SystemJS 0.17 release upgrade notes for more information, or read the updated SystemJS Overview guide.
Universal dynamic module loader - loads ES6 modules, AMD, CommonJS and global scripts in the browser and NodeJS. Works with both Traceur and Babel.
System.register bundle format for production, maintaining circular references support.Built on top of the ES6 Module Loader polyfill.
~15KB minified and gzipped, runs in IE8+ and NodeJS.
For discussion, see the Google Group.
For a list of guides and tools, see the Third-Party Resources Wiki.
<script src="system.js"></script>
<script>
// set our baseURL reference path
System.config({
baseURL: '/app'
});
// loads /app/main.js
System.import('main.js');
</script>
To load ES6, locate a transpiler (traceur.js, 'browser.js' from Babel, or 'typescript.js' from TypeScript)
in the baseURL path, then set the transpiler:
<script>
System.config({
// or 'traceur' or 'typescript'
transpiler: 'babel',
// or traceurOptions or typescriptOptions
babelOptions: {
}
});
</script>
Alternatively a custom path to Babel or Traceur can also be set through paths:
System.config({
map: {
traceur: 'path/to/traceur.js'
}
});
SystemJS relies on Promise being present in the environment.
For the best performance in IE and older browsers, it is advisable to load 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:
npm install traceur babel typescript
We can then load modules equivalently to in the browser:
var System = require('systemjs');
System.transpiler = 'traceur';
// loads './app.js' from the current directory
System.import('./app.js').then(function(m) {
console.log(m);
});
If using TypeScript, set global.ts = require('typescript') before importing to ensure it is loaded correctly.
If you are using jspm as a package manager you will also need to load the generated config.js. 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 System = require('jspm').Loader();
System.import('lodash').then(function (_) {
console.log(_);
});
Supported loader plugins:
Additional Plugins:
Guides:
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.
MIT
FAQs
Dynamic ES module loader
The npm package systemjs receives a total of 0 weekly downloads. As such, systemjs popularity was classified as not popular.
We found that systemjs demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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