jss-lite

Write stylesheets in JS.
Works with any stack.

There are many ways of writing styles as JS (Free Style, restyle and babel-plugin-css-in-js – just to name a few). But none of them except jss has the option to compile to a good old interoperable CSS stylesheet, or the new and shiny CSS module. I wanted an easy way to take advantage of JS goodness when writing stylesheets – a way compatible with any tech stack.

I wrote this library before I learned about jss (it was called css-in-js back then). It turns out that they do exactly the same thing – and much more. In turn, jss-lite offers an extremely simple, pure functional API without implicit state. We have less features than jss – but that means less developer overhead and better performance.

Installation

npm install [--save] jss-lite

Usage

const jssLite = require('jss-lite');

const indigo = '#3F51B5';

▸ jssLite({
    '.my-button': {
      'width': '50px',
      'background-color': indigo,
    },

    '@media screen and (min-width: 80em)': {
      '.my-button': {
        'width': '100%',
      },
    },
  });
◂ `
  .my-button {
    width: 50px;
    background-color: #3F51B5;
  }

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

Syntax

Any JS object is translated recursively to a CSS tree. To ensure two-way compatibility, we only support git.io/orthodox style objects.

Fonts and friends

Sometimes you need to define a block with the same pseudo-selector more than once in your stylesheet:

@font-face {
  font-family: "Merriweather Light";
  src: url("fonts/merriweather-light.woff") format("woff");
}

@font-face {
  font-family: "Merriweather Light";
  font-style: italic, oblique;
  src: url("fonts/merriweather-light-italic.woff") format("woff");
}

A JS object can’t have a @font-face key more than once – the latter overwrites the first one. Therefore we allow passing an array of objects:

▸ jssLite([{
    '@font-face': {
      'font-family': '"Merriweather Light"',
      'src': 'url("fonts/merriweather-light.woff") format("woff")',
    },
  }, {
    '@font-face': {
      'font-family': '"Merriweather Light"',
      'font-style': 'italic, oblique',
      'src': 'url("fonts/merriweather-light-italic.woff") format("woff")',
    },
  }]);
◂ `
  @font-face {
    font-family: "Merriweather Light";
    src: url("fonts/merriweather-light.woff") format("woff");
  }

  @font-face {
    font-family: "Merriweather Light";
    font-style: italic, oblique;
    src: url("fonts/merriweather-light-italic.woff") format("woff");
  }
  `

Fallbacks

When using fancy things which need a CSS fallback, you might want to set the same property more than once:

.drag-me {
  cursor: pointer;
  cursor: -webkit-grab;
  cursor: grab;
}

To cover these cases, we allow passing an array of style objects:

▸ jssLite({
    '.drag-me': [{
      cursor: 'pointer',
    }, {
      cursor: '-webkit-grab',
    }, {
      cursor: 'grab',
    }],
  });
◂ `
  .drag-me {
    cursor: pointer;
    cursor: -webkit-grab;
    cursor: grab;
  }
  `

Credits

jss-lite is heavily inspired by the great elm-css by Richard Feldman. The original name (css-in-js) comes from the disrupting React talk CSS in JS by Christopher Chedeau. The current name (jss-lite) is of course derived from our big brother jss.

License

MIT © Tomek Wiszniewski