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cxs

fast af css-in-js in 0.7kb

Build Status Coverage js-standard-style 0.7kb gzip

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

cxs is a minimal css-in-js solution that uses an atomic css approach to maximize performance and deduplication

Features

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: '32px',
  backgroundColor: 'tomato'
})

export default Box

Pseudoclasses

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

Media Queries

const className = cxs({
  fontSize: '32px',
  '@media screen and (min-width: 40em)': {
    fontSize: '48px'
  }
})

Child Selectors

const className = cxs({
  color: 'black',
  ' > a': {
    color: 'tomato'
  }
})

Static/Server-Side Rendering

For Node.js environments, use the css() method to return the static CSS string after rendering a view.

import React from 'react'
import ReactDOMServer from 'react-dom/server'
import cxs from 'cxs'
import App from './App'

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

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

// Reset the cache for the next render
cxs.reset()

Note: cxs does not currently have a mechanism for rehydrating styles on the client, so use with caution in universal JavaScript applications.

React Components

cxs also has an alternative higher order component API for creating styled React components, similar to the styled-components API.

import cxs from 'cxs/component'

const Heading = cxs('h1')({
  margin: 0,
  fontSize: '32px',
  lineHeight: 1.25
})

Extending components

To extend a cxs component, pass it to the component creator function.

const Button = cxs('button')({
  color: 'white',
  backgroundColor: 'blue'
})

const TomatoButton = cxs(Button)({
  backgroundColor: 'tomato'
})

Other components

Any component can be passed to cxs to add styles.

import { Link } from 'react-router'

const MyLink = cxs(Link)({
  color: 'tomato'
})

Note: components must accept className as a prop to work with cxs.

Functional styles

cxs components can also handle dynamic styling based on props by passing a function as an argument

const Heading = cxs('h1')(props => ({
  color: props.color
}))

Removing style props

To remove style props from the rendered HTML element, use the prop-types package to define propTypes on a component. cxs/component will remove any prop that matches a key from the propTypes object.

import cxs from 'cxs/component'
import PropTypes from 'prop-types'

const Heading = cxs('h2')(props => ({
  fontSize: props.big ? '48px' : '32px'
}))

Heading.propTypes = {
  big: PropTypes.bool
}

styled-system

Style utility functions, like those in styled-system, can be used with cxs/component.

import cxs from 'cxs/component'
import {
  space,
  color
} from 'styled-system'

const Heading = cxs('h2')(space, color)

Theming

Theming is supported with the <ThemeProvider> component.

import React from 'react'
import ThemeProvider from 'cxs/ThemeProvider'
import theme from './theme'

const App = props => (
  <ThemeProvider theme={theme}>
    <Heading>
      Hello
    </Heading>
  </ThemeProvider>
)

import cxs from 'cxs/component'

const Heading = cxs('h2')(props => ({
  fontSize: props.theme.fontSizes[4] + 'px',
  color: props.theme.blue
}))

API

cxs(...styles)

Accepts styles objects or functions that return style objects and returns a className string.

cxs.css()

Returns the rendered CSS string for static and server-side rendering.

cxs.reset()

Resets the cache for server-side rendering

cxs.prefix(val)

Updates the default class name prefix with the value passed to this function.

cxs/component

A styled-components-like API for creating React components with cxs.

Vendor prefixes

cxs does not handle vendor prefixing to keep the module size at a minimum.

Previous Versions

For previous versions of cxs, see the v3 branch or v4 branch

MIT License