React CSS components

Table of Contents

• Motivation
• Installation & Usage
• Base components
  • DOM components
  • Composite components
• Variants
  • Named variants
  • JavaScript expressions
• Customizing CSS loading
  • CSS extraction
  • Using with SASS/SCSS/LESS/Stylus/...
  • Using with PostCSS (including autoprefixer)

Motivation

Define React presentational components with CSS (or even SASS or Less if you like).

The implementation is based on CSS modules. In fact React CSS Components is just a thin API on top of CSS modules.

NOTE: The current implementation is based on Webpack but everything is ready to be ported onto other build systems (generic API is here just not yet documented). Raise an issue or better submit a PR if you have some ideas.

Installation & Usage

Install from npm:

% npm install react-css-components style-loader css-loader

Configure in webpack.config.js:

module.exports = {
  ...
  module: {
    loaders: [
      {
        test: /\.react.css$/,
        loader: 'react-css-components',
      }
    ]
  }
  ...
}

Now you can author React components in Styles.react.css:

Label {
  color: red;
}

Label:hover {
  color: white;
}

And consume them like regular React components:

import {Label} from './styles.react.css'

<Label /> // => <div class="<autogenerated classname>">...</div>

Base components

DOM components

By default React CSS Components produces styled <div /> components. You can change that by defining base: property:

FancyButton {
  base: button;
  color: red;
}

Now <FancyButton /> renders into <button />:

import {FancyButton} from './styles.react.css'

<FancyButton /> // => <button class="<autogenerated classname>">...</button>

Composite components

In fact any React component which accepts className props can be used as a base. That means that React CSS Components can be used as theming tool for any UI library.

Example:

DangerButton {
  base: react-ui-library/components/Button;
  color: red;
}

Variants

Variants is a mechanism which allows defining component styling variants.

Named variants

You can define additional styling variants for your components:

Label {
  color: red;
}

Label:emphasis {
  font-weight: bold;
}

They are compiled as CSS classes which then can be controlled from JS via variant prop:

<Label variant={{emphasis: true}} /> // sets both classes with `color` and `font-weight`

JavaScript expressions

You can define variants which are conditionally applied if JS expression against props evaluates to a truthy value.

Example:

Label {
  color: red;
}

Label:prop(mode == "emphasis") {
  font-weight: bold;
}

Note that any free variable references a member of props, thus in JS mode becomes props.mode in the example above.

They are compiled as CSS classes as well. JS expressions within prop(..) are used to determine if corresponding CSS classes should be applied to DOM:

<Label mode="emphasis" /> // sets both classes with `color` and `font-weight`

Customizing CSS loading

By default React CSS components loads CSS using style-loader!css-loader loader chain. That could be configured differently using loadCSS loader parameter.

This could be used to enable features such as CSS extraction, processing stylesheets with PostCSS/Autoprefixer or even authoring stylesheets with SASS or LESS.

CSS extraction

See the complete example which configures extract-text-webpack-plugin to extract stylesheets to a separate chunk.

Using with SASS/SCSS/LESS/Stylus/...

See the complete example which uses SASS/SCSS to create React components.

Using with PostCSS (including autoprefixer)

See the complete example which configures PostCSS with Autoprefixer to automatically add vendor prefixes to stylesheets.