Skip to content
This repository has been archived by the owner on Oct 9, 2020. It is now read-only.


Repository files navigation


CSS loading plugin


For installing with JSPM run:

jspm install css

For use with SystemJS natively, use:

npm install systemjs-plugin-css

Then add the configuration:

  map: {
    css: 'node_modules/systemjs-plugin-css/css.js'


To configure css files to load with the plugin set:

  meta: {
    '*.css': { loader: 'css' }

Or via package configuration as well:

  packages: {
    'src/': {
      meta: {
        '*.css': { loader: 'css' }

Modular CSS Concepts

CSS in the dependency tree implies a CSS modularisation where styles can be scoped directly to the render code that they are bundled with.

Just like JS requires, the order of CSS injection can't be guaranteed. The idea here is that whenever there are style overrides, they should be based on using a more specific selector with an extra id or class at the base, and not assuming a CSS load order. Reset and global styles are a repeated dependency of all modular styles that build on top of them.

CSS Transpilation

This plugin also acts as a base class that can be extended to author other CSS plugins such as LESS, modular CSS etc.

For example, see the plugin-less project.

Builder Support

When building with SystemJS Builder, by default CSS will be inlined into the JS bundle and injected on execution.

To alter this behaviour use the SystemJS configuration options:

  • separateCSS: true / false whether to build a CSS file at the same output name as the bundle itself to be included with a link tag. Defaults to false.
  • buildCSS: true / false whether to bundle CSS files or leave as separate requests. Defaults to true.
  • rootURL: Optional, local path that when set normalizes all CSS URLs to be absolute to this path.

Build Example

  var builder = require('systemjs-builder');

  // `builder.loadConfig` will load config from a file
  .then(function() {
    // additional config can also be set through `builder.config`
      separateCSS: true,
      rootURL: './public'

      // to disable css optimizations
      // cssOptimize: false

    return'myModule', 'bundle.js');

Will generate bundle.js containing the JS files and bundle.css containing the compressed CSS for the bundle.