Tailwind React Native Classnames 🏄‍♂️

A simple, expressive API for TailwindCSS + React Native, written in TypeScript

import { View, Text } from 'react-native';
import tw from 'twrnc';

const MyComponent = () => (
  <View style={tw`p-4 android:pt-2 bg-white dark:bg-black`}>
    <Text style={tw`text-md text-black dark:text-white`}>Hello World</Text>
  </View>
);

Features 🚀

• full support for all native RN styles with tailwind counterparts: (view, layout, image, shadow, and text).
• compatible with Tailwind CSS v3 and v2
• respects your tailwind.config.js for full configuration
• platform prefixes: android:mt-4 ios:mt-2
• dark mode support: bg-white dark:bg-black
• media query support: w-48 lg:w-64 (also, arbitrary: min-w-[600px]:flex-wrap)
• device orientation prefixes: portrait:flex-col landscape:flex-row
• vw and vh unit support: h-screen, min-w-screen, w-[25vw], etc...
• retina device pixel density prefix: w-4 retina:w-2
• arbitrary, JIT-style classes: mt-[31px] bg-[#eaeaea] text-red-200/75, etc...
• tagged template literal synax for most common usage
• merges supplied RN style objects for unsupported utilities or complex use cases
• supports custom utility creation via standard plugin config.
• heavily optimized for performance - styles resolved once, then stored in in-memory cache
• flexible, conditional styles based on classnames package api.
• written 100% in Typescript, ships with types

Docs:

• Installation
• API
• Customization
• Enabling Device-Context Prefixes
• Taking Control of Dark Mode
• Customizing Breakpoints
• Adding Custom Classes
• Matching Conditional Prefixes
• Box-Shadows
• RN-Only Additions
• JIT-style Arbitrary Values
• Migrating from V2
• Migrating from V1
• Prior Art

Installation

npm install twrnc

API

The default export is an ES6 Tagged template function which is nice and terse for the most common use case -- passing a bunch of space-separated Tailwind classes and getting back a react-native style object:

import tw from 'twrnc';

tw`pt-6 bg-blue-100`;
// -> { paddingTop: 24, backgroundColor: 'rgba(219, 234, 254, 1)' }

In the spirit of Tailwindcss's intuitive responsive prefix syntax, twrnc adds support for platform prefixes to conditionally apply styles based on the current platform:

// 😎 styles only added if platform matches
tw`ios:pt-4 android:pt-2`;

Media query-like breakpoint prefixes supported (see Breakpoints for configuration):

// 😎 faux media queries
tw`flex-col lg:flex-row`;

Dark mode support (see here for configuration);

// 😎 dark mode support
tw`bg-white dark:bg-black`;

You can also use tw.style() for handling more complex class name declarations. The api for this function is directly taken from the excellent classnames package.

// pass multiple args
tw.style('text-sm', 'bg-blue-100', 'flex-row mb-2');

// arrays of classnames work too
tw.style(['text-sm', 'bg-blue-100']);

// falsy stuff is ignored, so you can do conditionals like this
tw.style(isOpen && 'bg-blue-100');

// { [className]: boolean } style - key class only added if value is `true`
tw.style({
  'bg-blue-100': isActive,
  'text-red-500': invalid,
});

// or, combine tailwind classes with plain react-native style object:
tw.style('bg-blue-100', { resizeMode: `repeat` });

// mix and match input styles as much as you want
tw.style('bg-blue-100', ['flex-row'], { 'text-xs': true }, { fontSize: 9 });

If you need some styling that is not supported in a utility class, or just want to do some custom run-time logic, you can pass raw RN style objects to tw.style(), and they get merged in with the styles generated from any other utility classes:

tw.style(`mt-1`, {
  resizeMode: `repeat`,
  width: `${progress}%`,
});
// -> { marginTop: 4, resizeMode: 'repeat', width: '32%' }

The tw function also has a method color that can be used to get back a string value of a tailwind color. Especially useful if you're using a customized color pallette.

tw.color('blue-100'); // `bg|text|border-blue-100` also work
// -> "rgba(219, 234, 254, 1)"

You can import the main tw function and reach for tw.style only when you need it:

import tw from 'twrnc';

const MyComponent = () => (
  <View style={tw`bg-blue-100`}>
    <Text style={tw.style('text-md', invalid && 'text-red-500')}>Hello</Text>
  </View>
);

...or if the tagged template function isn't your cup of tea, just import tw.style as tw:

import { style as tw } from 'twrnc';

const MyComponent = () => (
  <View style={tw('bg-blue-100', invalid && 'text-red-500')}></View>
);

Customization

You can use twrnc right out of the box if you haven't customized your tailwind.config.js file at all. But more likely you've got some important app-specific tailwind customizations you'd like to use. For that reason, we expose the ability to create a custom configured version of the tw function object.

// lib/tailwind.js
import { create } from 'twrnc';

// create the customized version...
const tw = create(require(`../../tailwind.config.js`)); // <- your path may differ

// ... and then this becomes the main function your app uses
export default tw;

...and in your component files import your own customized version of the function instead:

// SomeComponent.js
import tw from './lib/tailwind';

⚠️ Make sure to use module.exports = {} instead of export default {} in your tailwind.config.js file, as the latter is not supported.

Enabling Device-Context Prefixes

To enable prefixes that require runtime device data, like dark mode, and screen size breakpoints, etc., you need to connect the tw function with a dynamic source of device context information. The library exports a React hook called useDeviceContext that takes care of this for you. It should be included one time, at the root of your component hierarchy, as shown below:

import tw from './lib/tailwind'; // or, if no custom config: `from 'twrnc'`
import { useDeviceContext } from 'twrnc';

export default function App() {
  useDeviceContext(tw); // <- 👋
  return (
    <View style={tw`bg-white dark:bg-black`}>
      <Text style={tw`text-black dark:text-white`}>Hello</Text>
    </View>
  );
}

Taking Control of Dark Mode

By default, if you use useDeviceContext() as outlined above, your app will respond to ambient changes in the device's color scheme (set in system preferences). If you'd prefer to explicitly control the color scheme of your app with some in-app mechanism, you'll need to configure things slightly differently:

import { useDeviceContext, useAppColorScheme } from 'twrnc';

export default function App() {
  // 1️⃣  opt OUT of listening to DEVICE color scheme events
  useDeviceContext(tw, { withDeviceColorScheme: false });

  // 2️⃣  use the `useAppColorScheme` hook to get a reference to the current color
  // scheme, with some functions to modify it (triggering re-renders) when you need to
  const [colorScheme, toggleColorScheme, setColorScheme] = useAppColorScheme(tw);

  return (
    {/* 3️⃣ use one of the setter functions, like `toggleColorScheme` in your app */}
    <TouchableOpacity onPress={toggleColorScheme}>
      <Text style={tw`text-black dark:text-white`}>Switch Color Scheme</Text>
    </TouchableOpacity>
  );
}

useAppColorScheme() accepts an optional second argument of an initial value for the color scheme. If not supplied, it will be initialized to the current system setting at the time the function is called.

Customizing Breakpoints

You can customize the breakpoints in the same way as a tailwindcss web project, using tailwind.config.js. The defaults that ship with tailwindcss are geared towards the web, so you likely want to set your own for device sizes you're interested in, like this:

// tailwind.config.js
module.exports = {
  theme: {
    screens: {
      sm: '380px',
      md: '420px',
      lg: '680px',
      // or maybe name them after devices for `tablet:flex-row`
      tablet: '1024px',
    },
  },
};

Adding Custom Classes

To add custom utilities, use the plugin method described in the tailwind docs, instead of writing to a .css file. twrnc provides a plugin() function you can use, but it's also compatible with the stock tailwindcss function:

// tailwind.config.js
const { plugin } = require('twrnc');

// or, you can use tailwinds plugin function:
const plugin = require('tailwindcss/plugin');

module.exports = {
  plugins: [
    plugin(({ addUtilities }) => {
      addUtilities({
        btn: {
          padding: 3,
          borderRadius: 10,
          textTransform: `uppercase`,
          backgroundColor: `#333`,
        },
        'resize-repeat': {
          resizeMode: `repeat`,
        },
      });
    }),
  ],
};

Wil also allow you to supply a string of other utility classes (similar to @apply), instead of using CSS-in-JS style objects:

module.exports = {
  plugins: [
    plugin(({ addUtilities }) => {
      addUtilities({
        // 😎 similar to `@apply`
        btn: `px-4 py-1 rounded-full bg-red-800 text-white`,
        'body-text': `font-serif leading-relaxed tracking-wide text-gray-800`,
      });
    }),
  ],
};

Matching Conditional Prefixes

twrnc also exposes a tw.prefixMatch(...prefixes: string[]) => boolean function that allows you to test whether a given prefix (or combination of prefixes) would produce a style given the current device context. This can be useful when you need to pass some primitive value to a component, and wish you could leverage tw's knowledge of the current device, or really anywhere you just need to do some logic based on the device context. This could also be accomplished by importing Platform or a combination of other RN hooks, but chances are you've already imported your tw function, and this saves you re-implementing all that logic on your own:

const SomeComponent = () => (
  <View>
    <Thumbnail imageSize={tw.prefixMatch(`portrait`) ? 60 : 90} />;
    {tw.prefixMatch(`ios`, `dark`) ? <CustomIosDarkModeThing /> : <Thing />}
  </View>
);

Box Shadows

Box shadows in CSS differ substantially from shadow in RN, so this library doesn't attempt to parse CSS box-shadow strings and translate them into RN style objects. Instead, it offers a number of low-level utilities not present in tailwindcss, which map to the 4 shadow props in RN:

// RN `shadowColor`
tw`shadow-white`; // > { shadowColor: `#fff` }
tw`shadow-red-200`; // > { shadowColor: `#fff` }
tw`shadow-[#eaeaea]`; // > { shadowColor: `#eaeaea` }
tw`shadow-black shadow-opacity-50`; // > { shadowColor: `rgba(0,0,0,0.5)` }

// RN `shadowOffset`
tw`shadow-offset-1`; // > { shadowOffset: { width: 4, height: 4 } }
tw`shadow-offset-2/3`; // > { shadowOffset: { width: 8, height: 12 } }
tw`shadow-offset-[3px]`; // > { shadowOffset: { width: 3, height: 3 } }],
tw`shadow-offset-[4px]/[5px]`; // > { shadowOffset: { width: 4, height: 5 } }],

// RN `shadowOpacity`
tw`shadow-opacity-50`; // { shadowOpacity: 0.5 }

// RN `shadowRadius`
tw`shadow-radius-1`; // { shadowRadius: 4 }
tw`shadow-radius-[10px]`; // { shadowRadius: 10 }

We also provide a default implementation of the shadow-<X> utils provided by tailwindcss, so you can use:

tw`shadow-md`;
/*
-> {
  shadowOffset: { width: 1, height: 1 },
  shadowColor: `#000`,
  shadowRadius: 3,
  shadowOpacity: 0.125,
  elevation: 3,
}
*/

To override the default implementations of these named shadow classes, add your own custom utilties -- any custom utilities you provide with the same names will override the ones this library ships with.

RN-Only Additions

twrnc implements all of the tailwind utilities which overlap with supported RN (native, not web) style props. But it also adds a sprinkling of RN-only utilities which don't map to web-css, including:

• low-level shadow utilities
• elevation (android only), eg: elevation-1, elevation-4
• small-caps -> {fontVariant: 'small-caps'}
• number based font-weight utilities font-100, font-400, (100...900)
• direction-(inherit|ltr|rtl)
• align-self: baseline; via self-baseline
• include-font-padding and remove-font-padding (android only: includeFontPadding)
• image tint color control (tint-{color} e.g. tint-red-200)

JIT-Style Arbitrary Values

Many of the arbitrary-style utilities made possible by Tailwind JIT are implemented in twrnc, including:

• arbitrary colors: bg-[#f0f], text-[rgb(33,45,55)]
• negative values: -mt-4, -tracking-[2px]
• shorthand color opacity: text-red-200/75 (red-200 at 75% opacity)
• merging color/opacity: border-black border-opacity-75
• arbitrary opacity amounts: opacity-73
• custom spacing: mt-[4px], -pb-[3px], tracking-[2px]
• arbitrary fractional insets: bottom-7/9, left-5/8
• arbitrary min/max width/height: min-w-[40%], max-h-3/8, w-[25vw], h-[21px]
• arbitrary breakpoints: min-w-[600px]:flex-row, max-h-[1200px]:p-4

Not every utility currently supports all variations of arbitrary values, so if you come across one you feel is missing, open an issue or a PR.

Migrating from V2

Color renames. In line with the upgrade guide, tailwind v3 has mapped green, yellow, and purple to their extended colors. Additionally, gray colors were renamed in the extended colors to be more specific. Both of these can be resolved by following tailwind's upgrade guide and optionally re-aliasing the colors in your tailwind.config.js.

Other than checking on any changes caused by color renames in tailwindcss, there are no breaking changes in V3 of this library, no further changes should be necessary.

New v3 prefixes and classes are being added as we identify use cases. If you do have a feature that would help your development, please open an issue and include any libraries / hooks that could help someone in the community put a PR together.

Migrating from V1

1. During the rewrite, the package name on npm was changed to twrnc. To remove the old library and install v2, run:

npm uninstall tailwind-react-native-classnames
npm install twrnc

2. Grep through your project replacing from 'tailwind-react-native-classnames' with from 'twrnc'.

3. If you were using a tailwind.config.js you can git rm your tw-rn-styles.json file, and switch to passing your config directly to create as shown below: (details here)

const tw = create(require(`../../tailwind.config.js`));

That's it! 🎉 The core API and functionality should work exactly the same from v1 to v2.

Prior Art

• The first version of this package (before it was re-written from scratch) was based heavily on the excellent vadimdemedes/tailwind-rn.
• The flexible tw.style() api was taken outright from classnames
• TailwindCSS
• Tailwind JIT
• React Native