A css-in-js webpack loader
JavaScript
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Readme.md

Travis – build status Coveralls – test coverage David – status of dependencies Code style: airbnb

jss-lite-loader

Write stylesheets in JS.
Works with any stack.

 

Installation

npm install [--save] jss-lite-loader

 

Usage

jss-lite-loader is very flexible. Feel free to combine it with other loaders – for example, style-loader for adding the styles to the page or apply-loader for configurable stylesheets.

Easy to use

You can use it like a good old CSS preprocessor like LESS or SASS:

∎ config.js

const color = require('color');

exports.buttonBackground =
  color('#F44336').alpha(0.5).lighten(0.5).rgbaColor();

∎ style.js

const { buttonBackground } = require('./config');

exports.stylesheet = {
  '.button': {
    'width': '50px',
    'background-color': buttonBackground,
  },

  '@media screen and (min-width: 80em)': {
    '.button': {
      'width': '100%',
    },
  },
};

∎ index.js

require('style!jss-lite!./style');

Sharing code between JS and CSS

Here’s a problem I encountered recently, which turned out to be a perfect match for jss-lite-loader. I use a bunch of brand-specific colors in my jss-lite stylesheets:

∎ header.js

const colors = require('material-colors');

const headerColor = exports.headerColor =
  materialColors.grey[800];

exports.stylesheet = {
  '.header': {
    'height': '60px',
    'background-color': headerColor,
  },
};

And here’s the wow. I can use the same values in JS for things CSS can’t do. For example, setting the theme-color:

∎ index.js

const h = require('hyperscript');

// This gets rendered and injected as CSS:
require('style!jss-lite!./header');

// The same file can be imported as a pure JS module, free of side effects:
const { headerColor } = require('./header');

document.head.appendChild(
  h('meta', { name: 'theme-color', content: headerColor })
);

Until now sharing variables between JS and CSS was notoriously difficult.

Flexible thus powerful

Because the API is so simple, you can add lots of features yourself. Here’s an example of unique, auto-generated class names and a configurable stylesheet function (for example, coming from a style framework) in a reusable hyperscript component. Whoah, that’s a lot at once!

∎ style.js

const hash = require('hash-sum')(__filename);

const classes = {
  button = `${hash}-button`,
};

module.exports = ({
  backgroundColor,
}) => ({ stylesheet: {
  [`.${classes.button}`]: {
    'width': '50px',
    'background-color': indigo,
  },

  '@media screen and (min-width: 80em)': {
    [`.${classes.button}`]: {
      'width': '100%',
    },
  },
} });

Object.assign(module.exports, { classes });

∎ button.js

require('style!jss-lite!apply?{ obj: { backgroundColor: "#F44336" } }!./style');
const { classes } = require('./style');

export default () => (
  h(`button.${classes.button}`)
);

 

License

MIT © Tomek Wiszniewski