Using Next.js with Expo for Web

A guide for integrating Next.js with Expo for the web.

Please open any issues related to Next.js with Expo at expo-cli/issues.

Next.js is a React framework that provides simple page-based routing as well as server-side rendering. To use Next.js with Expo for web we recommend that you use a library called @expo/next-adapter to handle the configuration and integration of the tools.

Using Expo with Next.js means you can share all of your existing components and APIs across your mobile and web. Next.js has its own webpack config so you'll need to start your web projects with the Next.js CLI and not with npx expo start.

Next.js can only be used with Expo for web, this doesn't provide Server-Side Rendering (SSR) for native apps.

TL;DR:

• Init: npx create-react-native-app -t with-nextjs (or npx create-next-app -e with-expo)
• Start: yarn next dev
• Open: http://localhost:3000/

Setup

To get started, create a new project with the template:

npx create-react-native-app -t with-nextjs

• Web: yarn next dev -- start the Next.js project
• Native: npx expo start -- start the Expo project

Add Next.js to Expo projects

This is for already existing Expo projects.

In this approach you would be using SSR for web in your universal project. This is the recommended path because it gives you full access to the features of Expo and Next.js.

Add Expo to Next.js projects

This is for already existing Next.js projects.

This approach is useful if you only want to use Expo components in your web-only project.

Manual setup

Optionally you can set the project up manually (not recommended).

Guides

Deploy to Vercel

(Formerly ZEIT Now)

This is Vercel's preferred method for deploying Next.js projects to production.

• Add a build script to your package.json

  {
    "scripts": {
      "build": "next build"
    }
  }
  

• Install the Vercel CLI: npm i -g vercel
• Deploy to Vercel: vercel

Polyfill setImmediate

Fixes setImmediate is not defined error.

A lot of libraries in the React ecosystem use the setImmediate() API (like react-native-reanimated), which Next.js doesn't polyfill by default. To fix this you can polyfill it yourself.

• Install: yarn add setimmediate
• Import in pages/_app.js, at the top of the file:

  import 'setimmediate';
  

If you restart the server this error should go away.

• Related issue and solution.

Image support

By default Next.js won't load your statically imported images (images that you include in your project with require('./path/to/image.png')) like an Expo project will. If you want to load static images into your <Image /> components or use react-native-svg then you can do the following:

• Install the plugin - yarn add next-images

  • next-images injects a webpack loader to handle images.
  • next-optimized-images is another good solution that you could check out.

• Wrap your Next.js configuration object with the image method and the Expo method in your next.config.js:

  const { withExpo } = require('@expo/next-adapter');
  const withImages = require('next-images');
  
  module.exports = withExpo(
    withImages({
      projectRoot: __dirname,
    })
  );
  

• Now restart your project and you should be able to load images!

You can test your config with the following example:

import React from 'react';
import { Image } from 'react-native';

export default function ImageDemo() {
  return <Image source={require('./assets/image.png')} style={{ flex: 1 }} />;
}

Font support

By default Next.js doesn't support static assets like an Expo project. Because this is the intended functionality of Next.js, @expo/next-adapter doesn't add font support by default. If you want to use libraries like expo-font, @expo/vector-icons, or react-native-vector-icons you'll need to change a few things.

• Install the plugin - yarn add next-fonts

  • next-fonts injects a webpack loader to handle fonts.

• Wrap the font method with the Expo method in your next.config.js:

  • The order is important because Expo can mix in the location of vector icons to the existing font loader.

  const { withExpo } = require('@expo/next-adapter');
  const withFonts = require('next-fonts');
  
  module.exports = withExpo(
    withFonts({
      projectRoot: __dirname,
    })
  );
  

• Now restart your project and you should be able to load fonts!

You can test your config with the following example:

import React, { useEffect, useState } from 'react';
import * as Font from 'expo-font';
import { Text } from 'react-native';

export default function FontDemo() {
  const [loaded, setLoaded] = useState(false);

  useEffect(() => {
    (async () => {
      try {
        await Font.loadAsync({
          // You can get this font on GitHub: https://shorturl.at/chEHS
          'space-mono': require('./assets/SpaceMono-Regular.ttf'),
        });
      } catch ({ message }) {
        // This will be called if something is broken
        console.log(`Error loading font: ${message}`);
      } finally {
        setLoaded(true);
      }
    })();
  }, []);

  if (!loaded) return <Text>Loading fonts...</Text>;

  return <Text style={{ fontFamily: 'space-mono' }}>Hello from Space Mono</Text>;
}

API

CLI

Generate static Next.js files into your project.

CLI Options

For more information run yarn next-expo --help (or -h)

Babel

The adapter provides a Babel config @expo/next-adapter/babel to simplify setup.

• Always use the universal babel-preset-expo
  • Provides React Native support for all platforms that Expo supports (web, iOS, Android)
• When running in the browser, also use next/babel preset.

Config

withExpo

Wraps your next.config.js and adds universal platform support.

• Defines a custom pageExtensions which makes webpack resolve .web.js before .js, we call this feature "platform extensions".
• Wraps the webpack config in withUnimodules from @expo/webpack-config
  • Makes Babel target all Expo, and React Native packages that you've installed
  • Aliases react-native to react-native-web in the browser
  • Defines the platform constants you get in React Native like __DEV__

const { withExpo } = require('@expo/next-adapter');

module.exports = withExpo({
  /* next.config.js code */
});

Document

Next.js uses the pages/_document.js file to augment your app's <html> and <body> tags. Learn more here.

This adapter provides a default Document (extended from Next.js's Document) that you can use to skip all of the React Native setup.

• Registers your app with AppRegistry from react-native-web to start your project.
• Implements the react-native-web CSS reset.

import Document, { style, getInitialProps } from '@expo/next-adapter/document';

Customizing the Document

If you need more control you can import then recompose the Document how you like. This is good for augmenting the <head /> element or mixing your own styles.

import { getInitialProps } from '@expo/next-adapter/document';
import Document, { Head, Main, NextScript } from 'next/document';
import React from 'react';

class CustomDocument extends Document {
  render() {
    return (
      <html>
        <Head>
          <meta httpEquiv="X-UA-Compatible" content="IE=edge" />
        </Head>
        <body>
          <Main />
          <NextScript />
        </body>
      </html>
    );
  }
}

// Import the getInitialProps method and assign it to your component to ensure the react-native-web styles are used.
CustomDocument.getInitialProps = getInitialProps;

// OR...

CustomDocument.getInitialProps = async props => {
  const result = await getInitialProps(props);
  // Mutate result...
  return result;
};

export default CustomDocument;

Limitations or differences comparing to the default Expo for Web

• To get PWA support, use Next.js plugins such as next-offline instead. Learn more here.
• You might need to use the next-transpile-modules plugin to transpile certain third-party modules in order for them to work (such as Emotion).
• Only the Next.js default page-based routing is supported. You'll need to use a completely different routing solution to do native navigation. We strongly recommend react-navigation for this.

Contributing

If you would like to help make Next.js support in Expo better, please feel free to open a PR or submit an issue:

• @expo/next-adapter

If you have any problems rendering a certain component with SSR then you can submit fixes to the expo/expo repo:

• Expo SDK packages