Expo is an open-source framework for apps that run natively on Android, iOS, and the web. Expo brings together the best of mobile and the web and enables many important features for building and scaling an app.
Expo is a set of tools built on top of React Native. The Nx Plugin for Expo contains generators for managing Expo applications and libraries within an Nx workspace.
Setting Up Expo
To create a new workspace with expo, run the following command:
npx create-nx-workspace --preset=expo
Adding Expo to an Existing Project
Install the expo plugin
npm i --save-dev @nx/expo
Creating Applications
Add a new application to your workspace with the following command:
nx g @nx/expo:app my-app
Start the application by running:
nx start my-app
Generating Libraries
To generate a new library run:
npx nx g @nx/expo:lib your-lib-name
Generating Components
To generate a new component inside library run:
npx nx g @nx/expo:component your-component-name --project=your-lib-name --export
Replace your-lib-name with the app's name as defined in your tsconfig.base.json file or the name property of your package.json
Using Expo
Start a Development Server
You can start a development server by running:
nx start <app-name>
Compile App Locally
You can compile your app locally with run-ios and run-android commands:
Compile for iOS:
nx run-ios <app-name>
To run these commands, you need to have your development environment setup. To run an iOS app,it can only be run on a Mac, and Xcode must be installed. Similarly, to run an Android app, it requires Android Studio and Java to be installed and configured on your computer. Setup steps: https://reactnative.dev/docs/environment-setup.
Compile Web Assets
You can build your JavaScript bundle using Metro bundler by running:
nx export <app-name>
Compile for all platforms:
nx export <app-name> --platform=all
Generate Native Code
To generate native code, run:
nx prebuild <app-name>
Generate for all platforms:
nx prebuild <app-name> --platform=all
Install Compatible NPM Packages
To install packages that is compatible with current version of Expo, run:
nx install <app-name>
Unlike npm's install command, this install command will install the exact right version for currently installed copy of Expo.
To install a specify NPM package, run:
nx install <app-name> --packages=<packpage-name>
nx install <app-name> --packages=<packpage-name-1>,<packpage-name-2>,<packpage-name-3>
To check and fix package versions, run:
Check which packages needed to be updated:
nx install <app-name> --check
Run an EAS Build
Expo Application Services (EAS) are deeply integrated cloud services for Expo and React Native apps. EAS Build is a hosted service for building app binaries for your Expo and React Native projects.
To run an EAS build:
nx build <app-name>
If you are not signed into an EAS account, run the following command to log in:
npx eas login
To check the details of your build status, run:
nx build-list <app-name>
Submit an EAS Build
EAS Submit is a hosted service for uploading and submitting your app binaries to the app stores. Since it's a hosted service, you can submit your app to both stores as long as you can run EAS CLI on your machine.
To submit an EAS build:
nx submit <app-name>
Update an EAS Build
EAS Update is a hosted service that serves updates for projects using the expo-updates library.
EAS Update makes fixing small bugs and pushing quick fixes a snap in between app store submissions. It accomplishes this by allowing an end-user's app to swap out the non-native parts of their app (for example, JS, styling, and image changes) with a new update that contains bug fixes and other updates.
To update an EAS build:
nx update <app-name>
Testing Projects
You can run unit tests with:
nx test <project-name>
Expo Commands
Below table is a map between expo commands and Nx commands:
| Expo Commands | Nx Commands |
|---|---|
expo start | nx start <app-name> |
expo run:ios | nx run-ios <app-name> |
expo run:android | nx run-android <app-name> |
expo export | nx export <app-name> |
expo prebuild | nx prebuild <app-name> |
expo install | nx install <app-name> |
eas build | nx build <app-name> |
eas build:list | nx build-list <app-name> |
eas update | nx update <app-name> |
eas submit | nx submit <app-name> |