# Tutorial: How to share code between iOS, Android & Web using React Native, react-native-web and monorepo

Bruno Lemos Updated on ・9 min read

Let's make our react-native app work in the browser, the right way.

This tutorial was last tested on react-native@0.61.x. If you are using a different version, some steps might need a little tweak

The code from this tutorial is available on GitHub: brunolemos/react-native-web-monorepo
You can fork it and use to start new projects with code sharing 🎉

## Why am I writing this?

Hi 👋 I'm Bruno Lemos. I recently launched a project called DevHub - TweetDeck for GitHub and one of the things that caught people's attention was the fact that it is an app made by a single developer and available on 6 platforms: Web (react-native-web), iOS (react native), Android (react native), macOS, Windows and Linux (electron, for now), with almost 100% code sharing between them. It even shares some code with the server! This is something that would require a team of 3+ until a couple years ago.

Since then, I've received dozens of tweets and private messages asking how to achieve the same and in this tutorial I'll walk you through it.

## What's react-native-web?

If you are not familiar with react-native-web, it's a lib by Necolas (ex Twitter engineer) to make your React Native code render in the browser. Roughly speaking, you will write <View /> and it will render <div />, making sure all styles render the exact same thing. It does more than that, but let's keep it simple.

The new Twitter was created using this technology and it's awesome.

If you already know react-native, you don't need to learn any new syntax. It's the same API.

## Summary

• Starting a new React Native project
• Turning our folder structure into a monorepo
• Making react-native work in a monorepo
• Sharing code between our monorepo packages
• Creating a new web project using create-react-app and react-native-web
• Making CRA work inside our monorepo with code sharing
• ???
• Profit

## Step-by-step tutorial

### Starting a new React Native project

• $react-native init myprojectname • $ cd myprojectname
• $git init && git add . -A && git commit -m "Initial commit" Note: It's much easier to create a cross platform app from scratch than trying to port an existing mobile-only (or even harder: web-only) project, since they may be using lot's of platform specific dependencies. EDIT: If you use expo, it seems they will soon have built in support for web! ### Turning our folder structure into a monorepo Monorepo means having multiple packages in a single repository so you can easily share code between them. It's a bit less trivial than it sounds because both react-native and create-react-app require some work to support monorepo projects. But hey, at least it's possible! We'll use a feature called Yarn Workspaces for that. Requirements: Node.js, Yarn and React Native • Make sure you are at the project root folder • $ rm yarn.lock && rm -rf node_modules
• $mkdir -p packages/components/src packages/mobile packages/web • Move all the files (except .git) to the packages/mobile folder • Edit the name field on packages/mobile/package.json from packagename to mobile • Create this package.json at the root directory to enable Yarn Workspaces: { "name": "myprojectname", "private": true, "workspaces": { "packages": [ "packages/*" ], "nohoist": [] } "dependencies": { "react-native": "0.61.3" } }  • Create a .gitignore at the root directory: .DS_Store .vscode node_modules/ yarn-error.log  • $ yarn

### Making react-native work in a monorepo

• Check where react-native got installed. If it was at /node_modules/react-native, all right. If it was at /packages/mobile/node_modules/react-native, something is wrong. Make sure you have the latest versions of node and yarn. Also make sure to use the exact same version of dependencies between the monorepo packages, e.g. "react": "16.11.0" on both mobile and components, not a different version between them.

• Open your favorite editor and use the Search & Replace feature to replace all occurrences of node_modules/react-native/ with ../../node_modules/react-native/.

• For react-native <= 0.59, open packages/mobile/package.json. Your start script currently ends in /cli.js start. Append this to the end: --projectRoot ../../.

• Open packages./mobile/metro.config.js and set the projectRoot field on it as well so it looks like this:

const path = require('path')

module.exports = {
projectRoot: path.resolve(__dirname, '../../'),
transformer: {
getTransformOptions: async () => ({
transform: {
experimentalImportSupport: false,
inlineRequires: false,
},
}),
},
}

• [Workaround] You currently need to add the react-native dependency to the root package.json to be able to bundle the JS:
  "dependencies": {
"react-native": "0.61.3"
},


#### iOS changes

• $open packages/mobile/ios/myprojectname.xcodeproj/ • Open AppDelegate.m, find jsBundleURLForBundleRoot:@"index" and replace index with packages/mobile/index • Still inside Xcode, click on your project name on the left, and then go to Build Phases > Bundle React Native code and Images. Replace its content with this: export NODE_BINARY=node export EXTRA_PACKAGER_ARGS="--entry-file packages/mobile/index.js" ../../../node_modules/react-native/scripts/react-native-xcode.sh  • $ yarn workspace mobile start

You can now run the iOS app! 💙 Choose one iPhone emulator and press the "Run" triangle button inside Xcode.

• $studio packages/mobile/android/ • Open packages/mobile/android/app/build.gradle. Search for the text project.ext.react = [...]. Edit it so it looks like this: project.ext.react = [ entryFile: "packages/mobile/index.js", root: "../../../../" ]  • Android Studio will show a Sync Now popup. Click on it. • Open packages/mobile/android/app/src/main/java/com/myprojectname/MainApplication.java. Search for the getJSMainModuleName method. Replace index with packages/mobile/index, so it looks like this: @Override protected String getJSMainModuleName() { return "packages/mobile/index"; }  If you get the Cannot get property 'packageName' on null object error, try disabling auto linking You can now run the Android app! 💙 Press the "Run" green triangle button inside Android Studio and choose the emulator or device. ### Sharing code between our monorepo packages We've created lots of folders in our monorepo, but only used mobile so far. Let's prepare our codebase for code sharing and then move some files to the components package, so it can be reused by mobile, web and any other platform we decide to support in the future (e.g.: desktop, server, etc.). • Create the file packages/components/package.json with the following contents: { "name": "components", "version": "0.0.1", "private": true }  • [optional] If you decide to support more platforms in the future, you'll do the same thing for them: Create a packages/core/package.json, packages/desktop/package.json, packages/server/package.json, etc. The name field must be unique for each one. • Open packages/mobile/package.json. Add all the monorepo packages that you are using as dependencies. In this tutorial, mobile is only using the components package: "dependencies": { "components": "0.0.1", ... }  • Stop the react-native packager if it's running • $ yarn
• $mv packages/mobile/App.js packages/components/src/ • Open packages/mobile/index.js. Replace import App from './App' with import App from 'components/src/App'. This is the magic working right here. One package now have access to the others! • Edit packages/components/src/App.js, replace Welcome to React Native! with Welcome to React Native monorepo! so we know we are rendering the correct file. • $ yarn workspace mobile start

Yay! You can now refresh the running iOS/Android apps and see our screen that's coming from our shared components package. 🎉

• $git add . -A && git commit -m "Monorepo" ## Web project Note: You can reuse up to 100% of the code, but that doesn't mean you should. It's recommended to have some differences between platforms to make them feel more natural to the user. To do that, you can create platform-specific files ending with .web.js, .ios.js, .android.js or .native.js. See example. ### Creating a new web project using CRA and react-native-web • $ cd packages/
• $npx create-react-app web • $ cd ./web (stay inside this folder for the next steps)
• $rm src/* (or manually delete all files inside packages/web/src) • Make sure the dependencies inside package.json are the exact same between all monorepo packages. For example, update the "react" version to "16.9.0" (or any other version) on both web and mobile packages. • $ yarn add react-native-web react-art
• $yarn add --dev babel-plugin-react-native-web • Create the file packages/web/src/index.js with the following contents: import { AppRegistry } from 'react-native' import App from 'components/src/App' AppRegistry.registerComponent('myprojectname', () => App) AppRegistry.runApplication('myprojectname', { rootTag: document.getElementById('root'), })  Note: when we import from react-native inside a create-react-app project, its webpack config automatically alias it to react-native-web for us. • Create the file packages/web/public/index.css with the following contents: html, body, #root, #root > div { width: 100%; height: 100%; } body { -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }  • Edit packages/web/public/index.html to include our CSS before closing the head tag: ... <title>React App</title> <link rel="stylesheet" href="%PUBLIC_URL%/index.css" /> </head>  ### Making CRA work inside our monorepo with code sharing CRA doesn't build files outside the src folder by default. We need to make it do it, so it can understand the code from our monorepo packages, which contains JSX and other non-pure-JS code. • Stay inside packages/web/ for the next steps • Create a .env file (packages/web/.env) with the following content: SKIP_PREFLIGHT_CHECK=true  • $ yarn add --dev react-app-rewired
• Replace the scripts inside packages/web/package.json with this:
"scripts": {
"start": "react-app-rewired start",
"build": "react-app-rewired build",
"test": "react-app-rewired test",
"eject": "react-app-rewired eject"
},

• Create the packages/web/config-overrides.js file with the following contents:
const fs = require('fs')
const path = require('path')
const webpack = require('webpack')

const appDirectory = fs.realpathSync(process.cwd())
const resolveApp = relativePath => path.resolve(appDirectory, relativePath)

// our packages that will now be included in the CRA build step
const appIncludes = [
resolveApp('src'),
resolveApp('../components/src'),
]

module.exports = function override(config, env) {
// allow importing from outside of src folder
config.resolve.plugins = config.resolve.plugins.filter(
plugin => plugin.constructor.name !== 'ModuleScopePlugin'
)
config.module.rules[0].include = appIncludes
config.module.rules[1] = null
config.module.rules[2].oneOf[1].include = appIncludes
config.module.rules[2].oneOf[1].options.plugins = [
require.resolve('babel-plugin-react-native-web'),
].concat(config.module.rules[2].oneOf[1].options.plugins)
config.module.rules = config.module.rules.filter(Boolean)
config.plugins.push(
new webpack.DefinePlugin({ __DEV__: env !== 'production' })
)

return config
}


The code above overrides some create-react-app's webpack config so it includes our monorepo packages in CRA's build step

• $git add . -A && git commit -m "Web project" That's it! You can now run yarn start inside packages/web (or yarn workspace web start at the root directory) to start the web project, sharing code with our react-native mobile project! 🎉 ## Some gotchas • react-native-web supports most of the react-native API, but a few pieces are missing like Alert, Modal, RefreshControl and WebView; • If you come across a dependency that doesn't work well with the monorepo structure, you can add it to the nohoist list; ## Some tips • Navigation may be a bit of a challenge; you can use something like react-navigation which recently added web support or you can try using two different navigators between and mobile, in case you want the best of both worlds by compromising some code sharing; • If you plan sharing code with the server, I recommend creating a core package that only contain logic and helper functions (no UI-related code); • For Next.js, you can check their official example with react-native-web • For native windows, you can try react-native-windows; • For native macOS, you can the new Apple Project Catalyst, but support for it is not 100% there yet (see my tweet); • To install new dependencies, use the command yarn workspace components add xxx from the root directory. To run a script from a package, run yarn workspace web start, for example; To run a script from all packages, run yarn workspaces run scriptname; Thanks for reading! 💙 If you like react, consider following me here on Dev.to and on Twitter. #### Links Posted on by: ### Bruno Lemos Open Source contributor. Software Engineer mostly using React Native, TypeScript, Redux & GraphQL. 💙 ### Discussion HELP! something changed and i cannot replicate this tutorial anymore. i cannot get past the first time you are testing android studio. I remember something like --version react-native@next that is now missing from this tutorial. and now i cannot replicate it at all some one please help. this is now the 7th time im following the instructions and i get this error first time i try test in the android simulator after trying to create monorepo Unable to resolve module ./packages/mobile/index Hi, I updated the tutorial with the latest changes from react-native@0.59, search for projectRoot to see the updated step involving the file metro.config.js. thank you so much for the new changes in the tutorial. i made the changes to the metro.config.js just like you suggested and i can now run it on android. i will continue with the rest of the tutorial in the morning. Hey Bruno how are you? Im still running into a issue. Soon as i complete the web section of the tutorial. my mono repo breaks for mobile. it installs all the modules in packages/mobile/node-modules instead of root/node_modules. Thus when I run packages/mobile/yarn start i get the following error "Error: Cannot find module 'E:\2019_PROJECTS\moco-messenger-project\code\repo\test\node_modules\react-native\local-cli\cli.js'" I dont understand how the web project is affecting the mobile project. Please assist. kind regards Make sure you have the correct content inside the root package.json and you used yarn at the root directory to install the dependencies, not inside each package neither npm instead of yarn. Compare your code with the repository to see if anything is different: github.com/brunolemos/react-native... hey bruno, I just did like you said, I even upgraded react-native to v0.59.0 stable. yet still when i run yarn in the root it still installs packages/mobile/node-modules and not in root/node_modules. how can i compare an entire project with difference in vs code? are you sure there isnt a step missing? I have tried 3 times now following your exact instructions. Do you have the latest version of nodejs and yarn? How is your root package.json? I just checked on my computer, im running yarn 1.130 and node v10.0.0 i believe those are the latest versions. my root package.json file looks exactly like yours. { "name": "myprojectname", "version": "0.0.1", "private": true, "workspaces": { "packages": [ "packages/*" ] } } like i said im extremely confused becasue i dont understand why the monorepo breaks when i add the web i just downloaded your project at github.com/brunolemos/react-native... and when i run yarn in the root it is also installing the packages in the wrong places. Hey everyone, I downloaded the project, followed the updated tutorial and ran into the same exact issue. I got /mobile running again by updating the relative filepath in its package.json to the react-native-cli: "scripts": { "start": "node ./node_modules/react-native/local-cli/cli.js start", "test": "jest" },  good luck! Hey, you both were right! React Native started getting installed inside packages/mobile/node_modules, which is wrong. Changing the path is not the right solution though. I investigated and you need to make sure all your dependencies have the exact same version between the monorepo packages. For example, change your "react" dependency inside the mobile and web's package.json to the exact same version (e.g. 16.8.4). This will make react-native get installed in the root node_modules again and also prevent multiple instances of react being installed in the same project, which would cause all kinds of bugs. Updated the tutorial and also the repository: github.com/brunolemos/react-native... Hi Bruno, How to use 3rd lib, I want to add react-native-element package. It's work well on mobile, but when I run web app, it's error below: Support for the experimental syntax 'classProperties' isn't currently enabled (41:23): 39 | 40 | export default class SwipeRating extends Component { > 41 | static defaultProps = { | ^ 42 | type: 'star', 43 | ratingImage: require('./images/star.png'), 44 | ratingColor: '#f1c40f', Add @babel/plugin-proposal-class-properties (https://git.io/vb4SL) to the 'plugins' section of your Babel config to enable transformation.  Here's what I added to config-override.js on packages/web const appIncludes = [ ... resolveApp('../../node_modules/react-native-elements'), resolveApp('../../node_modules/react-native-vector-icons'), ] module.exports = function override(config, env) { ... config.module.rules[2].oneOf[1].options.plugins = [ require.resolve('babel-plugin-react-native-web'), require.resolve('@babel/plugin-proposal-class-properties'), ].concat(config.module.rules[2].oneOf[1].options.plugins) ... }  In future, I will add react-navigation and some other packages. Please help, many thanks! Did you make it work? I haven't tried your code but yes, changing config-override.js correctly should be enough. Was anyone able to add react-navigation to the project? I got react-native-elements working by following the above comment. Here's a working example for React-Navigation with web : github.com/react-native-elements/r... Thank for documenting all this work thoroughly. As a React-Native noob, this guide was very easy to follow along ! Cheers! I got react-navigation's drawer working on the web. The following is my config-override.js const fs = require('fs') const path = require('path') const webpack = require('webpack') const appDirectory = fs.realpathSync(process.cwd()) const resolveApp = relativePath => path.resolve(appDirectory, relativePath) // our packages that will now be included in the CRA build step const appIncludes = [ resolveApp('src'), resolveApp('../components/src'), resolveApp('../../node_modules/@react-navigation'), resolveApp('../../node_modules/react-navigation'), resolveApp('../../node_modules/react-native-uncompiled'), resolveApp('../../node_modules/react-native-elements'), resolveApp('../../node_modules/react-native-gesture-handler'), resolveApp('../../node_modules/react-native-ratings'), resolveApp('../../node_modules/react-native-screens'), resolveApp('../../node_modules/react-native-tab-view'), resolveApp('../../node_modules/react-native-vector-icons'), resolveApp('../components/libraries/MSALAuthLogin'), resolveApp('../../node_modules/react-native-vector-icons'), ] module.exports = function override(config, env) { // allow importing from outside of src folder config.resolve.plugins = config.resolve.plugins.filter( plugin => plugin.constructor.name !== 'ModuleScopePlugin' ) config.module.rules[0].include = appIncludes config.module.rules[1] = null config.module.rules[2].oneOf[1].include = appIncludes config.module.rules[2].oneOf[1].options.plugins = [ require.resolve('babel-plugin-react-native-web'), require.resolve('@babel/plugin-proposal-class-properties'), ].concat(config.module.rules[2].oneOf[1].options.plugins) config.module.rules = config.module.rules.filter(Boolean) config.plugins.push( new webpack.DefinePlugin({ __DEV__: env !== 'production' }) ) return config }  thanks for the input i am facing similar issue while using GoogleSigninButton from react-native-google-signin. i tried adding require.resolve('@babel/plugin-proposal-class-properties') as you suggested below. also tried to update babel.config.js with the following, didnt worked as well... module.exports = { plugins: [ [ '@babel/plugin-proposal-decorators', { legacy: true, }, ], [ '@babel/plugin-proposal-class-properties', { loose: true, }, ], '@babel/plugin-syntax-dynamic-import', '@babel/plugin-transform-regenerator', [ '@babel/plugin-transform-runtime', { helpers: false, regenerator: true, }, ], ], presets: ['@babel/preset-flow', 'module:metro-react-native-babel-preset'], } also tried with loose: true require.resolve('@babel/plugin-proposal-class-properties', { loose: true, }), any suggestion please? thanks for you time. Hi Oz, were you able to make it run? Did you try with a compatible release (any before 0.60)? Hi Nishant, Unfortunately I was not able to solve it. I am not sure about earlier versions but I went over many possible suggestions, none of them worked... Any additional idea that I can try? Thanks for the reply Use this config to fix the issue config.module.rules.push( { test: /\.js$/,
use: {
options: {
babelrc: false,
configFile: false,

// The configration for compilation
presets: [
'@babel/preset-env',
'@babel/preset-react',
'@babel/preset-flow'
],
plugins: [
'@babel/plugin-proposal-class-properties',
]
}
}
}
)


Add the above code before the return config line

Thanks Rajendran

i tried adding the above as part of config-overrides.js
it didn't helped.

Under the folder 'react-native-web-monorepo/packages/components'
Is that the right location?

Thanks, Oz

An update...
i had to add two more dev dependencies under the web module.

now i am getting different error:
Attempted import error: 'requireNativeComponent' is not exported from 'react-native'.

With the react-native-version 0.60.4, I have some problems with libhermes.
When starting the android-app, it crashes and I always get the message: E/SoLoader: couldn't find DSO to load: libhermes.so. Any suggestions what to do?

Edit: Fixed my problem. You have to enable hermes, so that it looks like this in your build.gradle in app:
project.ext.react = [
entryFile: "packages/mobile/index.js",
root: "../../../../",
enableHermes: true, // clean and rebuild if changing
]

This works for me thanks!

You can run debug session from vscode with React Native Tools extension. But with monorepo its little hacky... btw, read-native run-its --project-path "./packages/mobile/ios" also work

I setup only iOS project with macos: you need to specify "runArguments": ["--project-path", "./packages/mobile/ios"] in debug task in launch.json and symlink with command:

ln -s /Users/proof666/Desktop/Projects/ShopList_new/PaperList/packages/mobile/ios  /Users/proof666/Desktop/Projects/ShopList_new/PaperList/ios


Update:

...
"runArguments": ["--root", "./packages/mobile"]


Thanks for sharing!

Hi Bruno, thanks for the awesome detailed tutorial with all the updates. And i can see you are very active in comments also which is awesome!

Its really nice to see react's progress towards PWA and cross platform portability.

I am following this tutorial to convert our old add(on Rn 0.59) over to react-native web. I followed this tutorial and setup everything up.
Than i copied the dependencies from our mobile repo's package json to packages/components/package.json. And all other code respectively in src. Idea was to get everything running on ios in this monorepo setup and than go from there to fix whatever needs to be fixed for web.

But i am getting some errors like first i got:

bundling failed: Error: Unable to resolve module path from /Users/..../projec/node_modules/react-native-dotenv/index.js: Module path does not exist in the Haste module map

Fixed it by adding path explicitly in dev-dependencies. Than started getting error:

bundling failed: Error: While trying to resolve module fs from file /Users/..../projec/node_modules/babel-plugin-dotenv/index.js, the package /Users/..../projec/node_modules/fs/package.json was successfully found. However, this package itself specifies a main module field that could not be resolved (/Users/..../projec/node_modules/fs/index.js. Indeed, none of these files exist

I am not very experienced in react and react-native, i am mainly on Ruby on Rails, so maybe this is something basic which i am getting wrong.
I found: stackoverflow.com/a/39046690/4738391 which suggests omething wrong with node environment or something. But i am a bit confused, i mean i can add these dependencies etc but it should work out of the box for mobile, as it was working fine in previous repo.

Any help will be greatly appreciated. Thanks.

After cache clean and everything, second error changed to:
error: bundling failed: Error: While trying to resolve module fs from file /Users/..../projec/node_modules/babel-plugin-dotenv/index.js, the package /Users/..../projec/node_modules/fs/package.json was successfully found. However, this package itself specifies a main module field that could not be resolved (/Users/..../projec/node_modules/fs/index.js. Indeed, none of these files exist

I was running into the same issue and I think I figured out the cause of the problem. I unfortunately don't know how to fix it. It seems to be related to react-native-cli not being able to locate the metro and babel configs because it's being run from the root of the repository.

Since they aren't found, when the bundler comes across react-native-dotenv within a source file it will actually import the source file rather than using the replacement provided by the babel plugin.

This was a stupid error, i had forgot to add 'module:react-native-dotenv' in my babel config presets. Adding it solved the problem and i got my mobile app compiled. There were some imports fixes etc in scode needed to be done to run app successfully. But that is done.

But now next errors(on web), i posted this SO question: stackoverflow.com/questions/571953...

If i can get any help, would be great.

Please remove all node_modules folders and .lock files from your project, clear all caches (xcode, —reset-cache, etc), and try following the steps again. Maybe you missed something.

You shouldn’t remove the dependencies from mobile. Check this repo source code and commit diffs: github.com/brunolemos/react-native...

After running yarn to install dependencies, check the contents of packages/mobile/node_modules, and let me know which folders it has. It shouldn’t have any, all should be in the root node_modules.

If nothing works, maybe they released a new version of the cli that broke something, in that case you can use a previous version or investigate the change.

I think i was not clear in my comment, actually it did work with barebone setup as described in this post. It was working perfectly, than i started exporting my mobile code, that's when it exploded.

I wanted to just have mobile app running as it is in this architecture. Than move un-convertable code to mobile and write replacement code for only those in web. But my mobile app is not running with these errors.

I did all the cache clear and everything but same issue. mobile repo's node_modules folder have 2 folder, .bin and metro-react-native-babel-preset.

I am pretty sure it is some of my mobile dependency. I don't know if i should share the package json etc and everything here. It will just get annoyingly long here.

Let me know if i should share that here, or i can reach you through some other medium.

I do understand this blog post is like THE go to blog right now for new projects which want to take this route. but porting old projects is a lot more messy. If i do succeed in porting my app on this architecture and support web, i will leave pointers and can also write an extension of this blog post.

Really great stuff, we learn a lot!

Here is what we wrote on somewhat the same topic.

reily.app/posts/2019-02-25/firebas...

It was too much trouble to set up both Android, iOS and their native dependencies in the mono repo structure.

So we decided to just nohoist everything. T_T

Nice, thanks for the mention in the article!

Were you able to share code between web and mobile using nohoist? I've had problems with this approach in the past but I don't remember exactly why. It has some downsides but it's definitely much simpler to setup. Everything working well for you this way?

No, sry for taking so long to reply.

Our yarn workspace is just set up to include app / backend / website

And they do not share components.

The problem is that metro does not support symbol links. Which is what yarn workspace uses.

scripts: {
"start": "node ../../node_modules/react-native/local-cli/cli.js start --projectRoot ../../"
}


throws error error: unknown option --projectRoot'

On modifying --projectRoot to --projectRoots I get following error

You mean when trying to use jest? If not please check the repository to see what you made differently.

Sorry, I modified my comment. I am getting an error with --projectRoot. I was trying on my own repo. I'll be cloning your repo and then let you know if the problem persists.

I'm using the unreleased react-native 0.59 in this tutorial, some dependencies got a major bump so maybe there are some differences if you are using an older version.

did you find an alternative for --projectRoot please ?

Number of issues here:
Changing jsBundleURLForBundleRoot:@"index" to jsBundleURLForBundleRoot:@"packages/mobile/index" leads to resolution errors
Leaving it as it is, leads to @babel/runtime/helpers/interopRequireDefault does not exist in the Haste module map. It looks like the packages/mobile/index reference is the way to go but that the react-native command uses packages/mobile as the ref location instead of the project root. From the root I tried two commands (RN 0.59):

mobile: start => ../../node_modules/.bin/react-native start --reset-cache
root: start => cd ./packages/mobile && yarn start
root: start => yarn workspace mobile start

In both cases, I get "Unable to resolve module ./packages/mobile/index from /Users/me/projects/rnw/packages/mobile/.
[...]
Indeed, none of these files exist:

• /Users/me/projects/rnw/packages/mobile/packages/mobile/index

Notice the duplicate packages/mobile reference

Ok, I identified the problem. The packages/mobile/metro.config.js is not processed. The projectRoot remains packages/mobile instead of 

Hi,

I'm facing the same problem. Did you manage to solve why the metro.config.js wasn't processed?

Current solution is to set --projectRoot ../../ at the package.json start script instead of metro.config.js, like it used to be before. Not sure if it's a bug or not.

Having some troubles getting react-native-web hoisted and getting everything to run. It insists on staying inside the web/node_modules together with fbjs and react. I do have some nohoist packages that are linked in the mobile project. I verified all the version numbers. They seem to be aligned

Tried various cleaning actions. I'm getting errors from hoisted elements not being able to find react-native-web shouldn't metro-react-native-babel-preset be implemented as a preset in the web project? This seems to be indicated in react-native-web examples

You need to use the exact same version of react between all package.json that have it.

Hey, thanks for your awesome tutorial. Just a quick question, how can we host the web version of the app? Cause it seem like it share the file inside the packages/component/src folder. I using Docker, is it mean that we need to add all files into the server?

The web package has a build command, and the result goes to the packages/web/dist folder. You should deploy only the dist folder.

I see.. thanks bro.. thats help a lot

Hi Bruno,

Great tutorial. Thanks for sharing.

Is it possible to maintain the each platform code in 3 different repo. Already I am having iOS and Android project. Now i would like to add some modules in react_native and integrate in iOS and Android. The thing is when the iOS and Android are inside the react-native root repo that is working fine. Linking also happening. But when I separate the iOS folder and when try to install the Pod i am getting issue as "cannot find module react_native/cli" in use_native_modules.

Kindly help me.

Thanks Bruno for this awesome post!! It was the only way I was able to make react-native work within a monorepo structure.

Currently I am working on a web + ios + tvos app and I was wondering how should I configure the tvos app since it react-native relies on npm:react-native-tvos@0.62.2-0. Following your tutorial I have:

1) Added 'react-native' and 'react-native/**' into tv package.json noHoist in order to get the react-native stored within the tv package and not use the ios hoisted one.

2) Use your metro.config.js configuration but also added the extraNodeModules in order to override the react-native alias to use the tv package one:

resolver: {
extraNodeModules: {
'react-native': path.resolve(__dirname, 'node_modules/react-native'),
},
}


3) Change the AppDelegate.m file with your configuration
4) Within the Bundle React Native code and Images section I have added the EXTRA_PACKAGER_ARGS but kept the react-native path as it is in order to use the tv package one:

export NODE_BINARY=node
export EXTRA_PACKAGER_ARGS="--entry-file packages/tv/index.js"
../node_modules/react-native/scripts/react-native-xcode.sh


Is this okay? Am I missing something else?

Thank you very much, your post is awesome <3!

Hello Bruno, awesome tutorial as I mentioned!

I have another question though, and it's related to builds. I've set the build phase as Release (so I can run it without a server) but I get an error in Xcode:

File /Users/--/Library/Developer/Xcode/DerivedData/project-name/Build/Products/Release-iphoneos/project-name.app/main.jsbundle does not exist. This must be a bug with'

Is there anything special I need to set here to get Xcode to build it?

No, this error is unrelated to this tutorial. Try cleaning the caches, e.g. Product > Clean and yarn start --reset-cache.

Thank you cheers! I had thought it was something related to the workspace edits. Turns out there's an issue in react-native about github.com/facebook/react-native/i....

So how did you fix it? I have the same issue. The GitHub issue link you provided is not working for me :-/

Thanks for the post! I have been able to get it going without any problems using the outlined steps.

I am facing problems however when i try to install 3rd party dependencies after getting the initial setup going. It will be great if the post could be updated with steps on how to install dependencies post setup.

For example i wanted to add react-native-gesture-handler and a few other native libraries but somehow i keep getting some issue or the other. I tried yarn workspace components add react-native-gesture-handler and it installs but i am unable to use it since i get IDE errors about some constants not being found. Similar issues with other libraries as well. Auto-linking somehow doesn't seem to reflect.

Should jettifier be installed and added in the post-install of package.json(and if so which package.json - root or the ones inside the packages) if running commands like yarn workspace mobile start? Basically some tips on how to add 3rd party libraries for both mobile and web will really help. Thanks again for the post - its my first attempt at a monorepo and this post really helped iron out all my initial doubts but i am also obviously making some newbie/rookie mistakes so there are some stumbling blocks to really get started with it.

Ok. so with a few more attempts i got it going for a critical dependency in my packages. I am using the versatile Navigation router (github.com/grahammendick/navigation) for all the routing requirements in all my packages, across all the router's supported platforms (which is basically everything web, mobile, native etc).

After following all the steps in the post i initially installed the router into my equivalent of the components package. I got it to work for the web but, for the react-native implementation, the navigation router has native code for Android and IoS and somehow it wasn't getting auto-linked. The solution was to simply install it to my equivalent of the mobile package and everything seems good! im still not sure of the jettifer post-install step but it should not be an issue i think.

Thanks a lot for this great tutorial.

ive probably missing it in the comments but i am not sure what pakage.json i should use for adding additional dependencies.
should i only update the root /package.json
or individually also

• packages/components/package.json
• packages/mobile/package.json
• packages/web/package.json

in addition, only yarn should be used?

Thanks again.

Yes only yarn because npm doesn’t have the “workspaces” feature.

You’ll add the dependencies in the package that’s using them. Most of it will probably be in the components. Don’t add at the root unless it’s things like lint etc.

Sir, will createBrowserApp(switchNavigator, { history: 'browser' }) work when I host a React Native Web app on GitHub Pages to have such these URLs:

Is it possible on GitHub Pages with React Native Web?

I recently worked on a project which used monorepo. It was my first introduction to it. I must say, I was not impressed. But hear me out. I've worked in the mobile app industry for over 10 years. I've seen architectures come and go.

Conceptually, I understand the use case for implementing such a design. In practice, I found it unintuitive, incredibly confusing, and slowed my project onboarding process to a crawl. I had six weeks to perform the job for which I was hired. The first week was spent wrapping my head around how to simply walk through the workflows. That cost the client a lot of money and reduced my available billable time by 20%. Imagine what would happen if the client had to onboard a less-experienced dev.

To be fair, there are a lot of unknowns here. It was my first hands-on with the design. Maybe the client's architect built it incorrectly? Would my experience have improved had the repo been better documented, i.e. had any doc at all? I don't really know.

I'm off that project and on my way to others. I will withhold judgment for now because this project could've been a fluke. I just wanted to interject my experience. For any non-trivial project, it's important for readers to remember that the business drives technology decisions. If a monorepo design pattern solves the particular business requirement, then I hope this tutorial helps you jumpstart your project.

Hi man, absolutely amazing tutorial, my dev team managed to get it up an running in no time.
However, we are facing two problems, one is related to babel plugins, no matter what i did, i could not add the @babel/plugin-transform-react-jsx, therefore the web package crashes:

../commons/pages/tabs/tabs.page.js
SyntaxError: /home/praetors/Projects/node/proyectoSembrar/packages/commons/pages/tabs/tabs.page.js: Support for the experimental syntax 'jsx' isn't currently enabled (16:9):

14 | const dummyTab = () => {
15 |     return (
> 16 |         <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
|         ^
17 |             <Text>Test</Text>
18 |         </View>
19 |     );

Add @babel/plugin-transform-react-jsx (https://git.io/vb4yd) to the 'plugins' section of your Babel config to enable transformation.


The other problem comes with react-native-vector-icons: ^7.0.0, we added the:

apply from: "../../../../node_modules/react-native-vector-icons/fonts.gradle"


but we could not get them to render in android, instead it shows the crossed box, here is how we implemented it:

import Icon from 'react-native-vector-icons/Ionicons';

export default function Tabs() {
return (
<Tab.Navigator
//...
screenOptions={({ route }) => ({
tabBarIcon: ({
focused, color, size
}) => {
let iconName;
switch (route.name) {
case 'Inicio':
iconName = focused ? 'ios-home' : 'ios-home-outline';
break;
//...
}
return <Icon name={iconName} size={size} color={color} />;
}
})}>
<Tab.Screen name="Inicio" component={Home} />
//...
</Tab.Navigator>
)
}


Hello Bruno,

1.) Now that Expo for Web was released, what would you recommend?
To setup a monorepo for Mobile and Web packages or to use Expo for Web?
There's also a React Native Web CLI called create-react-native-web-app.

2.) And also could you give some guide how to setup Next.js as a package of this monorepo? Upon running yarn create next-app --example with-react-native-web next, here's the response:

PS C:\Users\USERNAME\Documents\Node.js Projects\Samples\myprojectname\packages> yarn create next-app --example with-react-native-web next
yarn create v1.16.0
[1/4] Resolving packages...
[2/4] Fetching packages...
[4/4] Building fresh packages...
success Installed "create-next-app@0.5.9" with binaries:
- create-next-app
DEPRECATED (@octokit/rest): repos.getContent() is deprecated, use repos.getContents()

Installing npm modules:
react
react-dom
next

> Error! Failed to install react, react-dom, next, try again.
undefined
(node:12428) UnhandledPromiseRejectionWarning: Error: yarn installation failed
(node:12428) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:12428) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are
not handled will terminate the Node.js process with a non-zero exit code.
Done in 17.47s.


Thanks for any response!

Expo has it's own set of limitations, e.g. I've been using hooks in production since november 2018 and it only arrived in expo may 2019. If you are ok using expo go for it! They seem to be doing great progress.

About next, I don't know what the issue is, try creating the project separately and copy pasting the folder into the monorepo. Otherwise open an issue with them about monorepo support.

Hi,

I downloaded the repo, I am able to run the web app, but I have issue with ios
Can you tell me why I am getting the below issue, I am trying to do pod install inside my ios folder

aal003110384:ios reerer89989823\$ pod install

[!] Invalid Podfile file: cannot load such file -- /Users/reerer89989823/Desktop/codebase/Shipment/react-native-web-monorepo-master/packages/mobile/node_modules/@react-native-community/cli-platform-ios/native_modules.

# from /Users/reerer89989823/Desktop/codebase/Shipment/react-native-web-monorepo-master/packages/mobile/ios/Podfile:2
# -------------------------------------------
# platform :ios, '9.0'

require_relative '../node_modules/@react-native-community/cli-platform-ios/native_modules'
#

# -------------------------------------------

I want to discuss something we are facing after getting a great kickstart from this post. That is responsiveness problem.

We have made significant progress in our journey of converting existing RN apps to RNW. In-fact i am now writing a series of articles on my experience, first one was written last weekend and i plan on writing next this weekend. Here is the first part:
medium.com/@ziaulrehman/part-1-con...

For my use case, i am using a similar approach to this library: github.com/calinortan/react-getscreen it basically adds event handlers which trigger a state change hence re-render whenever screen size crosses one of pre-defined(configurable) widths.
This allows us to add conditional styles etc on some elements, or even hide/show some elements conditionally. This along with Platform.OS === 'web' is basically all we are doing for now. It doesn't look very clean but it works and gives us responsive design.

What techniques have you used(if any) for this? What worked best? And what would you suggest. Thanks.

I have a custom hook that checks the app dimensions and returns if it’s small/medium/large: github.com/devhubapp/devhub/blob/m...

Besides that, make sure to always use flexbox and percentages where makes sense, not fixed widths in pixels.

Yeah similar approach with HOC for class components. I actually just released a small RN component for this(actually my first npm package). npmjs.com/package/react-native-get...

When I use "yarn start", my web app works pretty much exactly the way it should. If I use "yarn build", and then "serve -s build", however, it gives me an error for createBrowserApp:

AppNavigator.ts:99 Uncaught TypeError: Object(...) is not a function


AppNavigator.ts:99 is:

const LoginNavigator = Platform.OS === 'web' ? createBrowserApp(loginStackNavigator) : createAppContainer(loginStackNavigator)


resolveApp('../../node_modules/react-navigation'),


I can't figure out why it works via "yarn start", but not on "yarn build". I've spent a while searching, and I can't seem to find an answer. Anyone have any ideas?

Hello,

Thank you so much for the article.

I have pulled down your repo, installed the deps and ran it. Metro bundler runs well but I do not see anything on the emulators.

Is there a step that I am missing?

Thanks

Siya

To run the mobile apps you can open Xcode/Android Studio and press the Run button.

Yeah, I realised that is how you were running it. I am a fan of the terminal, so I prefer that way. But for some reason I thought that running the bundler would mount the project into the emulator. Thank you so much for the article, I found it very helpful.

Thanks

Olá bruno, baixei a versão mais recente do monorepo, mas está dando esse erro,
sabe dizer porque? e como resolver?

[1] error: bundling failed: Error: Unable to resolve module ../../../commons/reducers/ from E:\sistemasagv\appwmsmobile\app-rf\packages\components\src\screen-mobile\Reducer\index.js: The module ../../../commons/reducers/ could not be found from E:\sistemasagv\a ppwmsmobile\app-rf\packages\components\src\screen-mobile\Reducer\index.js. Indeed, none of these files exist:
[1] * E:\sistemasagv\appwmsmobile\app-rf\packages\components\commons\reducers(.native||.android.js|.native.js|.js|.android.json|.native.json|.json|.android.ts|.native.ts|.ts|.android.tsx|.native.tsx|.tsx)
[1] * E:\sistemasagv\appwmsmobile\app-rf\packages\components\commons\reducers\index(.native||.android.js|.native.js|.js|.android.json|.native.json|.json|.android.ts|.native.ts|.ts|.android.tsx|.native.tsx|.tsx)
[1] at ModuleResolver.resolveDependency (E:\sistemasagv\appwmsmobile\app-rf\node_modules\metro\src\node-haste\DependencyGraph\ModuleResolution.js:163:15)
[1] at ResolutionRequest.resolveDependency (E:\sistemasagv\appwmsmobile\app-rf\node_modules\metro\src\node-haste\DependencyGraph\ResolutionRequest.js:52:18)
[1] at DependencyGraph.resolveDependency (E:\sistemasagv\appwmsmobile\app-rf\node_modules\metro\src\node-haste\DependencyGraph.js:283:16)
[1] at Object.resolve (E:\sistemasagv\appwmsmobile\app-rf\node_modules\metro\src\lib\transformHelpers.js:261:42)
[1] at dependencies.map.result (E:\sistemasagv\appwmsmobile\app-rf\node_modules\metro\src\DeltaBundler\traverseDependencies.js:399:31)
[1] at Array.map ()
[1] at resolveDependencies (E:\sistemasagv\appwmsmobile\app-rf\node_modules\metro\src\DeltaBundler\traverseDependencies.js:396:18)
[1] at E:\sistemasagv\appwmsmobile\app-rf\node_modules\metro\src\DeltaBundler\traverseDependencies.js:269:33
[1] at Generator.next ()
at asyncGeneratorStep (E:\sistemasagv\appwmsmobile\app-rf\node_modules\metro\src\DeltaBundler\traverseDependencies.js:87:24)

I tried to set up monorepo 2-3 months ago. Faced lots of errors with React Native. I have been searching for any decent material. I always suspected issue to be of old articles as the dependencies have changed. So the steps stated in the article or video were always not working for me.

I faced same stuff with your article. Tried it almost a year after you writing it.

I faced stackoverflow.com/questions/473994... issues everytime I tried to run the mobile app. This particular issue was extremely nasty github.com/facebook/react-native/i.... I never hated another library so much as React Native because of all this shit. Or some other module not popping up. I managed to get mobile app work only just once. But I couldn't get it to work when I imported the app from Components package. So I felt somehow my monorepo was not at all working. Almost all the stack overflow or github issues stated only few repeated solutions like clear cache, delete node_modules are re run it. In my scenario situation seemed to be deteoriating. Atleast mobile app was connecting to simulator, then after trying out these solutions it started giving the error of Metro server of not being up and running. Which didn't make sense simulator was able to make call metro server.

Then I thought atleast web would work but it didn't either it always gave me this error -
Module not found: Can't resolve 'react-native/Libraries/NewAppScreen. Because App.js in components package was using this library in updated version of React-Native CLI. I followed all the steps diligently I even found some more steps were required as well.

I don't know how you managed to get it to work. I really envy that but I have wasted too much time to just get the infrastructure setup managed to do total zero work. I worry if I try to integrate other libraries I'll face the same issues.

Just remove all the dummy components from react-native/Libraries/NewAppScreen. on the app.js screen. It will then work

Hi, after going through the steps listed under "ios changes" above, when i run "yarn workspace mobile start" it does launch the app in the simulator but i get a red screen with error (attaching image). Please help

Bruno, this is a great tutorial. I have been able to successfully migrate an existing react native project to the mono repository and can run and compile the mobile app for android. However, I am having issues building the web portion of the project. Any tips on how to debug? I am getting the project to start to compile but get in error Attempted import error: 'initStore' is not exported from '../store'. I have altered the index.js for web to pull in the components package.

Thanks

Is it possible to incrementally add rnw to an existing project?
The current project set up is a 3 package monorepo with redux being the only code that is shared. The goal is to share more code so I’m thinking to create a 4th package that only contains react native web components and is imported by the react and react native packages. Do you see any issues with this approach or pieces not working?

HELP!!!!!!

I have implemented react-navigation-drawer in my project. Just using two menu items there
( HomeScreen & ProfileScreen )

1. When the screen loaded first time ProfileScreen works perfectly but Second time it shows blank white screen on the browser. If I refresh screen then repeat the previous flow. First time works second time blank white screen.

1. The drawer not closing automatically on the browser ... but on mobile it works fine.

2. Can you please give me any reference where i can separate the style of web and mobile?

Hey, I'm looking at your articles(very comprehensive), among others, and trying to understand the need to add CRA to the stack, here. Would using react-native and react-native-web not do the trick?

Also, changing the import` statements in node_modules means you check in your node_modules? Or you make the edits every time you yarn install? (or, i missed smth with yarn workspaces 🤔?)

Thanks for your time and for the article!

CRA makes things easier, but it is not required.

It doesn't make any change inside node_modules, only on normal project files.