styled-jsx

What is styled-jsx?

The styled-jsx npm package is a CSS-in-JS library that allows you to write encapsulated and scoped CSS to style your components in a React application. It is specifically designed to work with React and Next.js and provides a way to include styles directly within JavaScript or TypeScript files.

What are styled-jsx's main functionalities?

Scoped Styles

This feature allows you to write CSS that is scoped to a component. The styles will not leak to other parts of the application.

<style jsx>{`p { color: red; }`}</style>

Global Styles

With styled-jsx, you can also define global styles that apply to the entire application, not just scoped to a single component.

<style jsx global>{`body { background: black; }`}</style>

Dynamic Styles

styled-jsx supports dynamic styles, allowing you to use JavaScript variables and expressions to determine the styles at runtime.

`<style jsx>{
  `p { color: ${color}; }`
}</style>`

Preprocessing

You can use preprocessors with styled-jsx to include external stylesheets or use features like nesting or variables.

<style jsx>{`
  @import 'styles/shared.css';
  p { color: red; }
`}</style>

Other packages similar to styled-jsx

styled-components

styled-components is another CSS-in-JS library that allows you to use template literals to write actual CSS code in your JavaScript files. It also handles scoping and supports dynamic styling. It differs from styled-jsx in its API and the way styles are applied to components.

emotion

Emotion is a performant and flexible CSS-in-JS library. It allows you to style applications quickly with string or object styles. It has a similar API to styled-components and includes features like composition, theming, and server-side rendering.

linaria

Linaria is a zero-runtime CSS-in-JS library that extracts CSS to separate files during the build process, rather than including styles in the JavaScript bundle. This can result in better performance compared to styled-jsx, which includes styles in the JS bundle.

README

styled-jsx

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

Code and docs are for v3 which we highly recommend you to try. Looking for styled-jsx v2? Switch to the v2 branch.

• Getting started
• Configuration options
  • optimizeForSpeed
  • sourceMaps
  • vendorPrefixes
• Features
• How It Works
  • Why It Works Like This
• Targeting The Root
• Global styles
  • One-off global selectors
• Dynamic styles
  • Via interpolated dynamic props
  • Via className toggling
  • Via inline style
• Constants
• Server-Side Rendering
  • styled-jsx/server
• External CSS and styles outside of the component
  • External styles
  • Styles outside of components
  • The resolve tag
  • Styles in regular CSS files
• CSS Preprocessing via Plugins
  • Plugin options
  • Example plugins
• Rendering in tests
• FAQ
  • Warning: unknown jsx prop on <style> tag
  • Can I return an array of components when using React 16?
  • Styling third parties / child components from the parent
  • Some styles are missing in production
  • Build a component library with styled-jsx
• Syntax Highlighting

Getting started

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>
)

Configuration options

The following are optional settings for the babel plugin.

optimizeForSpeed

Blazing fast and optimized CSS rules injection system based on the CSSOM APIs.

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

When in production* this mode is automatically enabled.
Beware that when using this option source maps cannot be generated and styles cannot be edited via the devtools.

* process.env.NODE_ENV === 'production'

sourceMaps

Generates source maps (default: false)

vendorPrefixes

Turn on/off automatic vendor prefixing (default: true)

Features

• Full CSS support, no tradeoffs in power
• Runtime size of just 3kb (gzipped, from 12kb)
• Complete isolation: Selectors, animations, keyframes
• Built-in CSS vendor 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"
• Source maps support
• Dynamic styles and themes support
• CSS Preprocessing via Plugins

How It Works

The example above transpiles to the following:

import _JSXStyle from 'styled-jsx/style'

export default () => (
  <div className="jsx-123">
    <p className="jsx-123">only this paragraph will get the style :)</p>
    <_JSXStyle styleId="123" css={`p.jsx-123 {color: red;}`} />
  </div>
)

Why It Works Like This

Unique classnames 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

Targeting The Root

Notice that the outer <div> from the example above also gets a jsx-123 classname. 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.

One-off global selectors

Sometimes it's useful to skip selectors scoping. In order to get a one-off global selector we support :global(), inspired by css-modules.

This is very useful in order to, for example, generate a global 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

To make a component's visual representation customizable from the outside world there are three options.

Via interpolated dynamic props

Any value that comes from the component's render method scope is treated as dynamic. This makes it possible to use props and state for example.

const Button = (props) => (
  <button>
     { props.children }
     <style jsx>{`
        button {
          padding: ${ 'large' in props ? '50' : '20' }px;
          background: ${props.theme.background};
          color: #999;
          display: inline-block;
          font-size: 1em;
        }
     `}</style>
  </button>
)

New styles' injection is optimized to perform well at runtime.

That said when your CSS is mostly static we recommend to split it up in static and dynamic styles and use two separate style tags so that, when changing, only the dynamic parts are recomputed/rendered.

const Button = (props) => (
  <button>
     { props.children }
     <style jsx>{`
        button {
          color: #999;
          display: inline-block;
          font-size: 2em;
        }
     `}</style>
     <style jsx>{`
        button {
          padding: ${ 'large' in props ? '50' : '20' }px;
          background: ${props.theme.background};
        }
     `}</style>
  </button>
)

Via className toggling

The second option 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

*best for animations

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

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>
)

Please keep in mind that constants defined outside of the component scope are treated as static styles.

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.

Content Security Policy

Strict CSP is supported.

You should generate a nonce per request.

import nanoid from 'nanoid'

const nonce = Buffer.from(nanoid()).toString('base64') //ex: N2M0MDhkN2EtMmRkYi00MTExLWFhM2YtNDhkNTc4NGJhMjA3

You must then pass a nonce to either flushToReact({ nonce }) or flushToHTML({ nonce }) and set a <meta property="csp-nonce" content={nonce} /> tag.

Your CSP policy must share the same nonce as well (the header nonce needs to match the html nonce and remain unpredictable). Content-Security-Policy: default-src 'self'; style-src 'self' 'nonce-N2M0MDhkN2EtMmRkYi00MTExLWFhM2YtNDhkNTc4NGJhMjA3';

External CSS and styles outside of the component

In styled-jsx styles can be defined outside of the component's render method or in separate JavaScript modules using the styled-jsx/css library. styled-jsx/css exports three tags that can be used to tag your styles:

• css, the default export, to define scoped styles.
• css.global to define global styles.
• css.resolve to define scoped styles that resolve to the scoped className and a styles element.

External styles

In an external file:

/* styles.js */
import css from 'styled-jsx/css'

// Scoped styles
export const button = css`button { color: hotpink; }`

// Global styles
export const body = css.global`body { margin: 0; }`

// Resolved styles
export const link = css.resolve`a { color: green; }`
// link.className -> scoped className to apply to `a` elements e.g. jsx-123
// link.styles -> styles element to render inside of your component

// Works also with default exports
export default css`div { color: green; }`

You can then import and use those styles:

import styles, { button, body } from './styles'

export default () => (
  <div>
    <button>styled-jsx</button>
    <style jsx>{styles}</style>
    <style jsx>{button}</style>
    <style jsx global>{body}</style>
  </div>
)

N.B. All the tags except for resolve don't support dynamic styles.

resolve and global can also be imported individually:

import { resolve } from 'styled-jsx/css'
import { global } from 'styled-jsx/css'

If you use Prettier we recommend you to use the default css export syntax since the tool doesn't support named imports.

Styles outside of components

The css tag from styled-jsx/css can be also used to define styles in your components files but outside of the component itself. This might help with keeping render methods smaller.

import css from 'styled-jsx/css'

export default () => (
  <div>
    <button>styled-jsx</button>
    <style jsx>{button}</style>
  </div>
)

const button = css`button { color: hotpink; }`

Like in externals styles css doesn't work with dynamic styles. If you have dynamic parts you might want to place them inline inside of your component using a regular <style jsx> element.

The resolve tag

The resolve tag from styled-jsx/css can be used when you need to scope some CSS and want back the generated scoped className and styles. This is usually the case when you want to style nested components from the parent.

import React from 'react'
import Link from 'some-library'

import css from 'styled-jsx/css'

const { className, styles } = css.resolve`
  a { color: green }
`

export default () => (
  <div>
    {/* use the className */}
    <Link className={className}>About</Link>
    {/* render the styles for it */}
    {styles}
    <style jsx>{`div { border: 5px solid green }`}</style>
  </div>
)

The resolve tag also supports dynamic styles:

import React from 'react'
import css from 'styled-jsx/css'

function getLinkStyles(color) {
  return css.resolve`
    a { color: ${color} }
  `
}

export default (props) => {
  const { className, styles } = getLinkStyles(props.theme.color)

  return (
    <div>
      <Link className={className}>About</Link>
      {styles}
    </div>
  )
}

Using resolve as a babel macro

The resolve tag can be used as a Babel macro thanks to the babel-plugin-macros system.

npm i --save styled-jsx
npm i --save-dev babel-plugin-macros

Next add babel-plugin-macros to your babel configuration:

{
  "plugins": [
    "babel-plugin-macros"
  ]
}

You can then start to use resolve by importing it from styled-jsx/macro.

import css, { resolve } from 'styled-jsx/macro'

const stylesInfo = css.resolve`a { color: green; }`
const stylesInfo2 = resolve`a { color: green; }`

Create React App comes with babel-plugin-macros pre-installed so you just need to install styled-jsx and you can start to use `resolve right away.

Styles in regular CSS files

styled-jsx v3 comes with a webpack loader that lets you write styles in regular css files and consume them in React.

import styles from '../components/button/styles.css'

export default () => (
  <div>
    <button>styled-jsx</button>
    <style jsx>{styles}</style>
  </div>
)

To consume the styles in your component you can import them from your CSS file and render them using a <style jsx> tag. Remember to add the global prop if you want your styles to be global.

To use this feature you need to register the loader in your webpack config file, before babel-loader which will then transpile the styles via styled-jsx/babel

config: {
  module: {
    rules: [
      test: /\.css$/,
      use: [{
        loader: require('styled-jsx/webpack').loader,
        options: {
          type: 'scoped'
        }
      }]
    ]
  }
}

The plugin accepts a type option to configure whether the styles should be scoped, global or resolve (see above). By default its values is set to scoped. type can also be a function which takes the file name that is being transpiled and must return a valid type.

type validTypes = 'scoped' | 'global' | 'resolve'
type fileName = string
type Options = {|
  type: validTypes | (fileName) => validTypes
|}

The type can also be set per individual CSS file via CSS comment:

/* @styled-jsx=scoped */

button { color: red }

The CSS comment option will override the one in the webpack configuration only for this specific file.

Next.js

Example of next.config.js to integrate styled-jsx/webpack:

module.exports = {
  webpack: (config, { defaultLoaders }) => {
    config.module.rules.push({
      test: /\.css$/,
      use: [
        defaultLoaders.babel,
        {
          loader: require('styled-jsx/webpack').loader,
          options: {
            type: 'scoped'
          }
        }
      ]
    })

    return config
  }
}

CSS Preprocessing via Plugins

Styles can be preprocessed via plugins.

Plugins are regular JavaScript modules that export a simple function with the following signature:

(css: string, options: Object) => string

Basically they accept a CSS string in input, optionally modify it and finally return it.

Plugins make it possible to use popular preprocessors like SASS, Less, Stylus, PostCSS or apply custom transformations to the styles at compile time.

To register a plugin add an option plugins for styled-jsx/babel to your .babelrc. plugins must be an array of module names or full paths for local plugins.

{
  "plugins": [
    [
      "styled-jsx/babel",
      { "plugins": ["my-styled-jsx-plugin-package", "/full/path/to/local/plugin"] }
    ]
  ]
}

Instructions to integrate with Next.js

In order to register styled-jsx plugins in a Next.js app you need to create a custom .babelrc file:

{
  "presets": [
    [
      "next/babel",
      {
        "styled-jsx": {
          "plugins": [
            "styled-jsx-plugin-postcss"
          ]
        }
      }
    ]
  ]
}

This is a fairly new feature so make sure that you using a version of Next.js that supports passing options to styled-jsx.

Plugins are applied in definition order left to right before styles are scoped.

In order to resolve local plugins paths you can use NodeJS' require.resolve.

N.B. when applying the plugins styled-jsx replaces template literals expressions with placeholders because otherwise CSS parsers would get invalid CSS E.g.

/* `ExprNumber` is a number */
%%styled-jsx-placeholder-ExprNumber%%

Plugins won't transform expressions (eg. dynamic styles).

When publishing a plugin you may want to add the keywords: styled-jsx and styled-jsx-plugin. We also encourage you to use the following naming convention for your plugins:

styled-jsx-plugin-<your-plugin-name>

Plugin options

Users can set plugin options by registering a plugin as an array that contains the plugin path and an options object.

{
  "plugins": [
    [
      "styled-jsx/babel",
      {
        "plugins": [
          ["my-styled-jsx-plugin-package", { "exampleOption":  true }]
        ],
        "sourceMaps": true
      }
    ]
  ]
}

Each plugin receives a options object as second argument which contains the babel and user options:

(css, options) => { /* ... */ }

The options object has the following shape:

{
  // user options go here
  // eg. exampleOption: true

  // babel options
  babel: {
    sourceMaps: boolean,
    vendorPrefixes: boolean,
    isGlobal: boolean,
    filename: ?string, // defined only when the filename option is passed to Babel, such as when using Babel CLI or Webpack
    location: { // the original location of the CSS block in the JavaScript file
      start: {
        line: number,
        column: number,
      },
      end: {
        line: number,
        column: number,
      }
    }
  }
}

Example plugins

The following plugins are proof of concepts/sample:

• styled-jsx-plugin-sass
• styled-jsx-plugin-postcss
• styled-jsx-plugin-stylelint
• styled-jsx-plugin-less
• styled-jsx-plugin-stylus

Rendering in tests

If you're using a tool such as Enzyme, you might want to avoid compiling your styles in test renders. In general, styled-jsx artifacts like jsx-123 classnames and vendor prefixing are not direct concerns of your component, and they generate a lot of snapshot noise.

One option is to exclude the styled-jsx/babel plugin from the test environment using env in your Babel config (see Config Merging options).

But this can cause noise in your terminal output when rendering:

   console.error node_modules/react-dom/cjs/react-dom.development.js:527
      Warning: Received `true` for a non-boolean attribute `jsx`.

The styled-jsx/babel-test solves this problem. It simply strips jsx attributes from all <style> tags. Be sure to target each environment with the appropriate plugin:

{
  "env": {
    "production": {
      "plugins": ["styled-jsx/babel"]
    },
    "development": {
      "plugins": ["styled-jsx/babel"]
    },
    "test": {
      "plugins": ["styled-jsx/babel-test"]
    }
  }
}

FAQ

Warning: unknown jsx prop on <style> tag

If you get this warning it means that your styles were not compiled by styled-jsx.

Please take a look at your setup and make sure that everything is correct and that the styled-jsx transformation is ran by Babel.

Can I return an array of components when using React 16?

No, this feature is not supported. However we support React Fragments, which are available in React 16.2.0 and above.

const StyledImage = ({ src, alt = '' }) => (
  <React.Fragment>
   <img src={src} alt={alt} />
   <style jsx>{`img { max-width: 100% }`}</style>
  </React.Fragment>
)

Styling third parties / child components from the parent

When the component accepts a className (or ad-hoc) prop as a way to allow customizations then you can use the resolve tag from styled-jsx/css.

When the component doesn't accept any className or doesn't expose any API to customize the component, then your only option is to use :global() styles:

export default () => (
  <div>
    <ExternalComponent />

    <style jsx>{`
      /* "div" will be prefixed, but ".nested-element" won't */

      div > :global(.nested-element) {
        color: red
      }
    `}</style>
  </div>
)

Please keep in mind that :global() styles will affect the entire subtree, so in many cases you may want to be careful and use the children (direct descendant) selector >.

Build a component library with styled-jsx

There's an article explaining how to bundle React components with Rollup and styled-jsx as an external dependency.

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>{)|(?<=css)":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.

Additionally you can use language injection comments to enable all the IDE language features indefinitely using the language comment style:

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

const Button = ({ children }) => (
  <button>
     { children }

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

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>"
   }
 }
}

Syntax Highlighting Visual Studio Code Extension

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

ext install vscode-styled-jsx

Autocomplete Visual Studio Code Extension

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

ext install vscode-styled-jsx-languageserver

Vim

Install vim-styled-jsx with your plugin manager of choice.

ESLint

If you're using eslint-plugin-import, the css import will generate errors, being that it's a "magic" import (not listed in package.json). To avoid these, simply add the following line to your eslint configuration:

"settings": {"import/core-modules": ["styled-jsx/css"] }

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)