@griffel/react

What is @griffel/react?

@griffel/react is a CSS-in-JS library designed to provide a performant and flexible way to style React components. It focuses on runtime performance and developer experience, offering features like atomic CSS, theming, and server-side rendering support.

What are @griffel/react's main functionalities?

Atomic CSS

Griffel generates atomic CSS classes for each style rule, ensuring minimal CSS output and better performance.

const useStyles = makeStyles({
  root: { color: 'red' },
  button: { backgroundColor: 'blue' }
});

function MyComponent() {
  const classes = useStyles();
  return (
    <div className={classes.root}>
      <button className={classes.button}>Click me</button>
    </div>
  );
}

Theming

Griffel supports theming, allowing you to define and use theme variables throughout your application.

const theme = {
  color: 'blue',
  background: 'lightgray'
};

const useStyles = makeStyles({
  root: theme => ({
    color: theme.color,
    backgroundColor: theme.background
  })
});

function MyComponent() {
  const classes = useStyles(theme);
  return <div className={classes.root}>Themed Component</div>;
}

Server-Side Rendering

Griffel supports server-side rendering, ensuring that styles are correctly rendered on the server and sent to the client.

import { renderToString } from 'react-dom/server';
import { GriffelProvider, makeStyles } from '@griffel/react';

const useStyles = makeStyles({
  root: { color: 'red' }
});

function MyComponent() {
  const classes = useStyles();
  return <div className={classes.root}>Hello SSR</div>;
}

const html = renderToString(
  <GriffelProvider>
    <MyComponent />
  </GriffelProvider>
);

Other packages similar to @griffel/react

styled-components

styled-components is a popular CSS-in-JS library that allows you to write actual CSS to style your components. It offers features like theming, automatic critical CSS, and server-side rendering. Compared to @griffel/react, styled-components focuses more on developer experience with a more expressive syntax but may have larger runtime overhead.

emotion

Emotion is another CSS-in-JS library that provides powerful and flexible styling capabilities. It offers both string and object styles, theming, and server-side rendering. Emotion is known for its performance and flexibility, making it a strong competitor to @griffel/react.

README

Griffel for React.js

A package with wrappers and APIs to be used with React.js.

• Install
• makeStyles()
  • Pseudo & class selectors, at-rules, global styles
  • Keyframes (animations)
  • CSS Fallback Properties
  • RTL support
• mergeClasses()
• makeStaticStyles()
• makeResetStyles()
• createDOMRenderer(), RendererProvider
  • compareMediaQueries
  • insertionPoint
  • styleElementAttributes
• TextDirectionProvider
• Shorthands
  • shorthands.borderColor
  • shorthands.borderStyle
  • shorthands.borderWidth

Install

npm install @griffel/react
# or
yarn add @griffel/react

makeStyles()

Is used to define styles, returns a React hook that should be called inside a component:

import { makeStyles } from '@griffel/react';

const useClasses = makeStyles({
  button: { color: 'red' },
  icon: { paddingLeft: '5px' },
});

function Component() {
  const classes = useClasses();

  return (
    <div>
      <button className={classes.button} />
      <span className={classes.icon} />
    </div>
  );
}

Pseudo & class selectors, at-rules, global styles

makeStyles() supports pseudo, class selectors and at-rules.

import { makeStyles } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    ':active': { color: 'pink' },
    ':hover': { color: 'blue' },
    // :link, :focus, etc.

    '.foo': { color: 'black' },
    ':nth-child(2n)': { backgroundColor: '#fafafa' },

    '@media screen and (max-width: 992px)': { color: 'orange' },
    '@container (max-width: 992px)': { color: 'orange' },
    '@container foo (max-width: 992px)': { color: 'orange' },
    '@supports (display: grid)': { color: 'red' },
    '@layer utility': { marginBottom: '1em' },
  },
});

Another useful feature is :global() selector, it allows connecting local styles with global selectors.

import { makeStyles } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    ':global(html[data-whatintent="mouse"])': { backgroundColor: 'yellow' },
    // outputs: html[data-whatintent="mouse"] .abcd { background-color: yellow }
  },
});

Keyframes (animations)

keyframes are supported via animationName property that can be defined as an object or an array of objects:

import { makeStyles } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    animationIterationCount: 'infinite',
    animationDuration: '3s',
    animationName: {
      from: { transform: 'rotate(0deg)' },
      to: { transform: 'rotate(360deg)' },
    },
  },
  array: {
    animationIterationCount: 'infinite',
    animationDuration: '3s',
    animationName: [
      {
        from: { transform: 'rotate(0deg)' },
        to: { transform: 'rotate(360deg)' },
      },
      {
        from: { height: '100px' },
        to: { height: '200px' },
      },
    ],
  },
});

CSS Fallback Properties

Any CSS property accepts an array of values which are all added to the styles. Every browser will use the latest valid value (which might be a different one in different browsers, based on supported CSS in that browser):

import { makeStyles } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    overflowY: ['scroll', 'overlay'],
  },
});

RTL support

Griffel uses rtl-css-js to perform automatic flipping of properties and values in Right-To-Left (RTL) text direction defined by TextDirectionProvider.

import { makeStyles } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    paddingLeft: '10px',
  },
});

⬇️⬇️⬇️

/* Will be applied in LTR */
.frdkuqy {
  padding-left: 10px;
}
/* Will be applied in RTL */
.f81rol6 {
  padding-right: 10px;
}

You can also control which rules you don't want to flip by adding a /* @noflip */ CSS comment to your rule:

import { makeStyles } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    paddingLeft: '10px /* @noflip */',
  },
});

⬇️⬇️⬇️

/* Will be applied in LTR & RTL */
.f6x5cb6 {
  padding-left: 10px;
}

mergeClasses()

💡 It is not possible to simply concatenate classes returned by useClasses().

There are cases where you need to merge classes from multiple useClasses calls.

To properly merge the classes, you need to use mergeClasses() function, which performs merge and deduplication of atomic classes generated by makeStyles().

import { mergeClasses, makeStyles } from '@griffel/react';

const useClasses = makeStyles({
  blueBold: {
    color: 'blue',
    fontWeight: 'bold',
  },
  red: {
    color: 'red',
  },
});

function Component() {
  const classes = useClasses();

  const firstClassName = mergeClasses(classes.blueBold, classes.red); // { color: 'red', fontWeight: 'bold' }
  const secondClassName = mergeClasses(classes.red, classes.blueBold); // { color: 'blue', fontWeight: 'bold' }

  return (
    <>
      <div className={firstClassName} />
      <div className={secondClassName} />
    </>
  );
}

makeStaticStyles()

Creates styles attached to a global selector. Styles can be defined via objects:

import { makeStaticStyles } from '@griffel/react';

const useStaticStyles = makeStaticStyles({
  '@font-face': {
    fontFamily: 'Open Sans',
    src: `url("/fonts/OpenSans-Regular-webfont.woff2") format("woff2"),
         url("/fonts/OpenSans-Regular-webfont.woff") format("woff")`,
  },
  body: {
    background: 'red',
  },

  /**
   * ⚠️ nested and pseudo selectors are not supported for this scenario via nesting
   *
   * Not supported:
   * .some {
   *   .class { ... },
   *   ':hover': { ... }
   * }
   *
   * Supported:
   * '.some.class': { ... }
   * '.some.class:hover': { ... }
   */
});

function App() {
  useStaticStyles();

  return <div />;
}

Or with string & arrays of strings/objects:

import { makeStaticStyles } from '@griffel/react';

const useStaticStyles1 = makeStaticStyles('body { background: red; } .foo { color: green; }');
const useStaticStyles2 = makeStaticStyles([
  {
    '@font-face': {
      fontFamily: 'My Font',
      src: `url(my_font.woff)`,
    },
  },
  'html { line-height: 20px; }',
]);

function App() {
  useStaticStyles1();
  useStaticStyles2();

  return <div />;
}

makeResetStyles()

Atomic CSS has tradeoffs. Once an element has many HTML class names each pointing to different CSS rules, browser layout times slow down.

There are cases when it's reasonable to flatten multiple declarations into monolithic CSS. For example, base styles for components in a UI library. Rules generated by makeResetStyles() are inserted into the CSS style sheet before all the Atomic CSS, so styles from makeStyles() will always override these rules.

makeResetStyles returns a React hook that should be called inside a component:

import { makeStyles, makeResetStyles } from '@griffel/react';
import { mergeClasses } from './mergeClasses';

const useBaseClass = makeResetStyles({
  color: 'red',
  padding: 0,
  // etc.
});

const useClasses = makeStyles({
  primary: { color: 'blue' },
  circular: {
    padding: '5px',
    borderRadius: '5px',
  },
});

function Component(props) {
  const baseClass = useBaseClass();
  const classes = useClasses();

  return (
    <button className={mergeClasses(baseClass, props.primary && classes.primary, props.circular && classes.circular)} />
  );
}

⚠️ Only one class generated by makeResetStyles() can be applied to an element. Otherwise, behavior will be non-deterministic as classes merging will not be done for this case and results depend on order of insertion.

import { makeStyles } from '@griffel/react';

const useClassA = makeResetStyles({
  /* styles */
});
const useClassB = makeResetStyles({
  /* styles */
});

function Component(props) {
  /* 💣 Never apply multiple rules from makeResetStyles() to the same element */
  return <button className={mergeClasses(useClassA(), useClassB())} />;
}

createDOMRenderer(), RendererProvider

createDOMRenderer is paired with RendererProvider component and is useful for child window rendering and SSR scenarios. This is the default renderer for web, and will make sure that styles are injected to a document.

import { createDOMRenderer, RendererProvider } from '@griffel/react';

function App(props) {
  const { targetDocument } = props;
  const renderer = React.useMemo(() => createDOMRenderer(targetDocument), [targetDocument]);

  return (
    <RendererProvider renderer={renderer} targetDocument={targetDocument}>
      {/* Children components */}
      {/* ... */}
    </RendererProvider>
  );
}

compareMediaQueries

A function with the same signature as sort functions in e.g. Array.prototype.sort for dynamically sorting media queries. Maps over an array of media query strings.

Griffel does not provide an opinionated default to sort media queries as the order may vary depending on the specific needs of the application.

import { createDOMRenderer } from '@griffel/react';

const mediaQueryOrder = [
  'only screen and (min-width: 1366px)',
  'only screen and (min-width: 1366px)',
  'only screen and (min-width: 1920px)',
];

function sortMediaQueries(a, b) {
  return mediaQueryOrder.indexOf(a) - mediaQueryOrder.indexOf(b);
}

const renderer = createDOMRenderer(document, {
  compareMediaQueries,
});

<html>
  <head>
    <style media="only screen and (min-width: 1024px)" data-make-styles-bucket="m"></style>
    <style media="only screen and (min-width: 1366px)" data-make-styles-bucket="m"></style>
    <style media="only screen and (min-width: 1920px)" data-make-styles-bucket="m"></style>
  </head>
</html>

For mobile-first methodology, you can consider using sort-css-media-queries:

import { createDOMRenderer } from '@griffel/react';
import sortCSSmq from 'sort-css-media-queries';

const renderer = createDOMRenderer(document, {
  compareMediaQueries: sortCSSmq,
});

<html>
  <head>
    <style media="only screen and (min-width: 1px)" data-make-styles-bucket="m"></style>
    <style media="only screen and (min-width: 480px)" data-make-styles-bucket="m"></style>
    <style media="only screen and (min-width: 640px)" data-make-styles-bucket="m"></style>
  </head>
</html>

insertionPoint

If specified, a renderer will insert created style tags after this element:

import { createDOMRenderer } from '@griffel/react';

const insertionPoint = document.head.querySelector('#foo');
const renderer = createDOMRenderer(document, {
  insertionPoint,
});

<html>
  <head>
    <style id="foo" />
    <!-- Style elements created by Griffel will be inserted after "#foo" element -->
    <style data-make-styles-bucket="d" />
    <style id="bar" />
  </head>
</html>

styleElementAttributes

A map of attributes that's passed to the generated style elements. For example, is useful to set "nonce" attribute.

import { createDOMRenderer } from '@griffel/react';

const renderer = createDOMRenderer(document, {
  styleElementAttributes: {
    nonce: 'random',
  },
});

TextDirectionProvider

TextDirectionProvider is used to determine the text direction for style computation. The default text direction is Left-To-Right (LTR).

import { TextDirectionProvider } from '@griffel/react';

function App() {
  return (
    <>
      <TextDirectionProvider>
        {/* Inner components will have styles for LTR */}
        {/* ... */}
      </TextDirectionProvider>
      <TextDirectionProvider dir="rtl">
        {/* Inner components will have styles for RTL */}
        {/* ... */}
      </TextDirectionProvider>
    </>
  );
}

Shorthands

shorthands provides a set of functions to mimic CSS shorthands and improve developer experience as some of CSS shorthands are not supported by Griffel.

shorthands.borderColor

import { makeStyles, shorthands } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    ...shorthands.borderColor('red'),
    ...shorthands.borderColor('red', 'blue'),
    ...shorthands.borderColor('red', 'blue', 'green'),
    ...shorthands.borderColor('red', 'blue', 'green', 'yellow'),
  },
});

shorthands.borderStyle

import { makeStyles, shorthands } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    ...shorthands.borderStyle('solid'),
    ...shorthands.borderStyle('solid', 'dashed'),
    ...shorthands.borderStyle('solid', 'dashed', 'dotted'),
    ...shorthands.borderStyle('solid', 'dashed', 'dotted', 'double'),
  },
});

shorthands.borderWidth

import { makeStyles, shorthands } from '@griffel/react';

const useClasses = makeStyles({
  root: {
    ...shorthands.borderWidth('12px'),
    ...shorthands.borderWidth('12px', '24px'),
    ...shorthands.borderWidth('12px', '24px', '36px'),
    ...shorthands.borderWidth('12px', '24px', '36px', '48px'),
  },
});