Package Exports

cxs
cxs/atomic
cxs/monolithic

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (cxs) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

CXS

Functional CSS for functional UI components

const className = cxs({ color: 'tomato' })

CXS is a functional CSS-in-JS solution that uses atomic styles to maximize deduplication and help with dead code elimination.

Features

Three different modes of operation:
- Atomic
- Lite
- Monolithic
~6KB
Avoids collisions with atomic rulesets
Deduplicates repeated styles
Dead-code elimination
Framework independent
CSS-in-JS
- Media queries
- Pseudoclasses
- Nested selectors
- Avoid maintaining separate stylesheets
- Use plain JS objects and types
- No tagged template literals

Install

npm install cxs

Usage

CXS works with any framework, but this example uses React for demonstration purposes.

import React from 'react'
import cxs from 'cxs'

const Box = (props) => {
  return (
    <div
      {...props}
      className={className} />
  )
}

const className = cxs({
  padding: 32,
  backgroundColor: 'tomato'
})

export default Box

Pseudoclasses

cxs({
  color: 'tomato',
  ':hover': {
    color: 'red'
  }
})

Media Queries

cxs({
  color: 'tomato',
  '@media (min-width: 40em)': {
    color: 'red'
  }
})

Nested Selectors

cxs({
  color: 'tomato',
  h1: {
    color: 'red'
  }
})

Server-Side Rendering

To use CXS in server environments, use the css() function to get the static CSS string after rendering a view.

import React from 'react'
import ReactDOMServer from 'react-dom/server'
import cxs, { css, reset } from 'cxs'
import App from './App'

const html = ReactDOMServer.renderToString(<App />)

const doc = `<!DOCTYPE html>
<style>${css()}</style>
${html}
`

// reset the cache for the next render
reset()

Modes

CXS offers three different modes of operation, which produce different rules and class names.

import cxsAtomic from 'cxs'
import cxsMonolithic from 'cxs/monolithic'
import cxsLite from 'cxs/lite'

const styles = {
  margin: 0,
  marginBottom: 32,
  padding: 16,
  color: 'tomato',
  ':hover': {
    color: 'orangered'
  },
  '@media (min-width: 40em)': {
    padding: 32
  }
}

// Each mode returns a different set of class names

cxsAtomic(styles)
// m-0 mb-32 p-16 c-tomato -hover-c-orangered _zsp35u

cxsMonolithic(styles)
// _q5nmba

cxsLite(styles)
// a b c d e f

Atomic Mode (Default)

import cxs from 'cxs'

The default mode is the atomic mode. This creates atomic rulesets and attempts to create human readable classnames. If a classname is longer than 24 characters, a hashed classname will be used instead.

Lite Mode

import cxs from 'cxs/lite'

For super fast performance, use the cxs/lite module. Lite mode creates alphabetic class names in a sequential order and does not support nested selectors.

Since the class names in cxs/lite are not created in a functional manner, when using cxs/lite on both the server and client, the styles will need to be rehydrated. Rehydration is not yet implemented.

Monolithic Mode

import cxs from 'cxs/monolithic'

To create encapsulated monolithic styles with CXS and use single hashed class names, import the monolithic module.

The monolithic module also accepts custom selectors for styling things like the body element.

cxs('body', {
  fontFamily: '-apple-system, sans-serif',
  margin: 0,
  lineHeight: 1.5
})

API

import cxs, {
  css,
  sheet,
  reset
} from 'cxs'
// Creates styles and returns micro classnames
cxs({ color: 'tomato' })

// Returns a CSS string of attached rules. Useful for server-side rendering
css()

// The threepointone/glamor StyleSheet instance
// See https://github.com/threepointone/glamor
cxs.sheet

// Clear the cache and flush the glamor stylesheet.
// This is useful for cleaning up in server-side contexts.
cxs.reset()

How it Works

The CXS function creates a separate rule for each declaration, adds CSS rules to a style tag in the head of the document, and returns multiple classnames.

The returned classname is based on the property and value of the declaration. Some classnames are abbreviated, and long classnames are hashed.

cxs({ color: 'tomato' })
// c-tomato

Vendor prefixes

CXS does not handle vendor prefixing to keep the module size at a minimum. To add vendor prefixes, use a prefixing module like inline-style-prefixer

import cxs from 'cxs'
import prefixer from 'inline-style-prefixer/static'

const prefixed = prefixer({
  display: 'flex'
})
const cx = cxs(prefixed)

Browser support

IE9+, due to the following:

Array.filter
Array.map
Array.reduce
Array.forEach

MIT License