css-modulesify

A browserify plugin to load CSS Modules.

Please note that this is still highly experimental.

Why CSS Modules?

Normally you need to use a strict naming convention like BEM to ensure that one component's CSS doesn't collide with another's. CSS Modules are locally scoped, which allows you to use names that are meaningful within the context of the component, without any danger of name collision.

Read Mark Dalgleish's excellent "End of Global CSS" and check out css-modules for more context.

Getting started

First install the package: npm install --save css-modulesify

Then you can use it as a browserify plugin, eg: browserify -p [ css-modulesify -o dist/main.css ] example/index.js

Inside example/index.js you can now load css into your scripts. When you do var box1 = require('./box1.css'), box1 will be an object to lookup the localized classname for one of the selectors in that file.

So to apply a class to an element you can do something like:

var styles = require('./styles.css');
var div = `<div class="${styles.inner}">...</div>`;

The generated css will contain locally-scoped versions of any css you have require'd, and will be written out to the file you specify in the --output or -o option.

API Usage

var b = require('browserify')();

b.add('./main.js');
b.plugin(require('css-modulesify'), {
  rootDir: __dirname,
  output: './path/to/my.css'
});

b.bundle();

Options:

• rootDir: absolute path to your project's root directory. This is optional but providing it will result in better generated classnames.
• output: path to write the generated css.
• jsonOutput: optional path to write a json manifest of classnames.
• use: optional array of postcss plugins (by default we use the css-modules core plugins).

Using CSS Modules on the backend

If you want to use CSS Modules in server-generated templates there are a couple of options:

• Option A (nodejs only): register the require-hook so that var styles = require('./foo.css') operates the same way as on the frontend. Make sure that the rootDir option matches to guarantee that the classnames are the same.

• Option B: configure the jsonOutput option with a file path and css-modulesify will generate a JSON manifest of classnames.

PostCSS Plugins

The following PostCSS plugins are enabled by default:

• postcss-modules-local-by-default
• postcss-modules-extract-imports
• postcss-modules-scope

(i.e. the CSS Modules specification).

You can override the default PostCSS Plugins (and add your own) by passing --use|-u to css-modulesify.

Or if you just want to add some extra plugins to run after the default, add them to the postcssAfter array option (API only at this time).

In addition you may also wish to configure defined PostCSS plugins by passing --plugin.option true.

An example of this would be:

browserify -p [css-modulesify \
  --after autoprefixer --autoprefixer.browsers '> 5%' \
  -o dist/main.css] -o dist/index.js src/index.js

Example

An example implementation can be found here.

Licence

MIT

With thanks

• Tobias Koppers
• Mark Dalgleish
• Glen Maddern

---

Josh Johnston, 2015.