@fatfisz/styled-jsx

styled-jsx

Full, scoped and component-friendly CSS support for JSX (rendered on the server or the client).

Usage

Firstly, install the package:

$ npm install --save styled-jsx

Next, add styled-jsx/babel to plugins in your babel configuration:

{
  "plugins": [
    "styled-jsx/babel"
  ]
}

Now add <style jsx> to your code and fill it with CSS:

export default () => (
  <div>
    <p>only this paragraph will get the style :)</p>
    { /* you can include <Component />s here that include
         other <p>s that don't get unexpected styles! */ }
    <style jsx>{`
      p {
        color: red;
      }
    `}</style>
  </div>
)

Features

• Full CSS support, no tradeoffs in power
• Runtime size of just 2kb (gzipped, from 6kb)
• Complete isolation: Selectors, animations, keyframes
• Built-in CSS-prefixing
• Very fast, minimal and efficient transpilation (see below)
• High-performance runtime-CSS-injection when not server-rendering
• Future-proof: Equivalent to server-renderable "Shadow CSS"
• Works like the deprecated <style scoped>, but the styles get injected only once per component

How It Works

The example above transpiles to the following:

import _JSXStyle from 'styled-jsx/style'

export default () => (
  <div data-jsx='cn2o3j'>
    <p data-jsx='cn2o3j'>only this paragraph will get the style :)</p>
    <_JSXStyle styleId='cn2o3j' css={`p[data-jsx=cn2o3j] {color: red;}`} />
  </div>
)

Why It Works Like This

Data attributes give us style encapsulation and _JSXStyle is heavily optimized for:

• Injecting styles upon render
• Only injecting a certain component's style once (even if the component is included multiple times)
• Removing unused styles
• Keeping track of styles for server-side rendering (discussed in the next section)

Targeting The Root

Notice that the parent <div> above also gets a data-jsx atribute. We do this so that you can target the "root" element, in the same manner that :host works with Shadow DOM.

If you want to target only the host, we suggest you use a class:

export default () => (
  <div className="root">
    <style jsx>{`
      .root {
        color: green;
      }
    `}</style>
  </div>
)

Global styles

To skip scoping entirely, you can make the global-ness of your styles explicit by adding global.

export default () => (
  <div>
    <style jsx global>{`
      body {
        background: red
      }
    `}</style>
  </div>
)

The advantage of using this over <style> is twofold: no need to use dangerouslySetInnerHTML to avoid escaping issues with CSS and take advantage of styled-jsx's de-duping system to avoid the global styles being inserted multiple times.

Global selectors

Sometimes it's useful to skip prefixing. We support :global(), inspired by css-modules.

This is very useful in order to, for example, generate an unprefixed class that you can pass to 3rd-party components. For example, to style react-select which supports passing a custom class via optionClassName:

import Select from 'react-select'
export default () => (
  <div>
    <Select optionClassName="react-select" />

    <style jsx>{`
      /* "div" will be prefixed, but ".react-select" won't */
      div :global(.react-select) {
        color: red
      }
    `}</style>
  </div>
)

Dynamic styles

Via className toggling

To make a component's visual representation customizable from the outside world, there are two options. The first one is to pass properties that toggle class names.

const Button = (props) => (
  <button className={ 'large' in props && 'large' }>
     { props.children }
     <style jsx>{`
        button {
          padding: 20px;
          background: #eee;
          color: #999
        }
        .large {
          padding: 50px
        }
     `}</style>
  </button>
)

Then you would use this component as either <Button>Hi</Button> or <Button large>Big</Button>.

Via inline style

Imagine that you wanted to make the padding in the button above completely customizable. You can override the CSS you configure via inline-styles:

const Button = ({ padding, children }) => (
  <button style={{ padding }}>
     { children }
     <style jsx>{`
        button {
          padding: 20px;
          background: #eee;
          color: #999
        }
     `}</style>
  </button>
)

In this example, the padding defaults to the one set in <style> (20), but the user can pass a custom one via <Button padding={30}>.

Constants and Config

It is possible to use constants like so:

import { colors, spacing } from '../theme'
import { invertColor } from '../theme/utils'

const Button = ({ children }) => (
  <button>
     { children }
     <style jsx>{`
        button {
          padding: ${ spacing.medium };
          background: ${ colors.primary };
          color: ${ invertColor(colors.primary) };
        }
     `}</style>
  </button>
)

N.B. Only constants defined outside of the component scope are allowed here. If you want to use or toggle dynamic values depending on the component state or props then we recommend to use one of the techniques from the Dynamic styles section

Server-Side Rendering

styled-jsx/server

The main export flushes your styles to an array of React.Element:

import React from 'react'
import ReactDOM from 'react-dom/server'
import flush from 'styled-jsx/server'
import App from './app'

export default (req, res) => {
  const app = ReactDOM.renderToString(<App />)
  const styles = flush()
  const html = ReactDOM.renderToStaticMarkup(<html>
    <head>{ styles }</head>
    <body>
      <div id="root" dangerouslySetInnerHTML={{__html: app}} />
    </body>
  </html>)
  res.end('<!doctype html>' + html)
}

We also expose flushToHTML to return generated HTML:

import React from 'react'
import ReactDOM from 'react-dom/server'
import { flushToHTML } from 'styled-jsx/server'
import App from './app'

export default (req, res) => {
  const app = ReactDOM.renderToString(<App />)
  const styles = flushToHTML()
  const html = `<!doctype html>
    <html>
      <head>${styles}</head>
      <body>
        <div id="root">${app}</div>
      </body>
    </html>`
  res.end(html)
}

It's paramount that you use one of these two functions so that the generated styles can be diffed when the client loads and duplicate styles are avoided.

Syntax Highlighting

When working with template literals a common drawback is missing syntax highlighting. The following editors currently have support for highlighting CSS inside <style jsx> elements.

If you have a solution for an editor not on the list please open a PR and let us now.

Atom

The language-babel package for the Atom editor has an option to extend the grammar for JavaScript tagged template literals.

After installing the package add the code below to the appropriate settings entry. In a few moments you should be blessed with proper CSS syntax highlighting. (source)

"(?<=<style jsx>{)|(?<=<style jsx global>{)":source.css.styled

Webstorm/Idea

The IDE let you inject any language in place with Inject language or reference in an Intention Actions (default alt+enter). Simply perform the action in the string template and select CSS. You get full CSS highlighting and autocompletion and it will last until you close the IDE.

Emmet

If you're using Emmet you can add the following snippet to ~/emmet/snippets-styledjsx.json This will allow you to expand style-jsx to a styled-jsx block.

{
 "html": {
   "snippets": {
     "style-jsx": "<style jsx>{`\n\t$1\n`}</style>"
   }
 }
}

Visual Studio Code Extension

Launch VS Code Quick Open (⌘+P), paste the following command, and press enter.

ext install vscode-styled-jsx

Autocomplete

By now, this extension doesn't support autocomplete. However, you can install ES6 Template Literal Editor extension to edit styles in another pane, and you will get full feature of css language service provided by VS Code.

Credits

• Pedram Emrouznejad (rijs) suggested attribute selectors over my initial class prefixing idea.
• Sunil Pai (glamor) inspired the use of murmurhash2 (minimal and fast hashing) and an efficient style injection logic.
• Sultan Tarimo built stylis.js, a super fast and tiny CSS parser and compiler.
• Max Stoiber (styled-components) proved the value of retaining the familiarity of CSS syntax and pointed me to the very efficient stylis compiler (which we forked to very efficiently append attribute selectors to the user's css)
• Yehuda Katz (ember) convinced me on Twitter to transpile CSS as an alternative to CSS-in-JS.
• Evan You (vuejs) discussed his Vue.js CSS transformation with me.
• Henry Zhu (babel) helpfully pointed me to some important areas of the babel plugin API.

Authors

• Guillermo Rauch (@rauchg) - ▲ZEIT
• Naoyuki Kanezawa (@nkzawa) - ▲ZEIT
• Giuseppe Gurgone (@giuseppegurgone)