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React Native using Expo and Typescript

This is a React Native demo app using the Expo framework and written in TypeScript. It uses the managed workflow.

This repo used to also contain a type definition file for Expo. That work was merged into the @types/expo package. @types/expo is now deprecated in favor of definition types includes with the expo package. TypeScript FTW!

Screen shot

Prerequisites

  • Node.js.
  • Yarn.
  • Optional: XCode, since it includes the iOS Simulator. XCode only runs on Macs.
  • Optional: Android Studio, since it includes the Android Virtual Device Manager.

You don't need to install any global npm packages for this repo. expo-cli is included as a dev dependency.

Warnings When Installing Packages

There are a surprising amount of of warnings when installing Node packages, because of peer dependencies not being correct. My guess is that the Expo team has a tough time getting all the added React Native libraries to play well together. This app seems to run fine, so I believe it's safe to ignore the warnings.

Running the App

Start the local server. This will give you a QR code that you can scan using the Expo Client app on your mobile device.

yarn start

If you're on a Mac and have Xcode installed, you can run the app using the iOS Simulator with the following command. I am sure you can do something similar with Android.

yarn ios

Packages

List of the packages that this project uses. I really wish it was possible to write comments in package.json.

When upgrading Expo, expo-cli will also upgrade the versions of all the package that it knows about. This list naturally includes all the expo- packages, but also a few more. Do not change the version numbers of the known packages. Unknown packages may be upgraded. More info in my blog post Upgrade an Expo App.

Package Name Known? Notes
@babel/core Known Peer dependency.
@react-navigation/native Used to navigate between screens.
@react-navigation/stack Used to navigate between screens.
@types/react Known
@types/react-native Known
@typescript-eslint/eslint-plugin Add TypeScript support to ESLint.
@typescript-eslint/parser Add TypeScript support to ESLint.
babel-preset-expo Known Configure Babel for Expo.
eslint Linter.
eslint-config-prettier Prettier rules for ESLint.
eslint-plugin-prettier Run prettier through ESLint. TODO: Is this used?
eslint-plugin-react React rules for ESLint.
expo Known
expo-analytics-amplitude Known Used by AmplitudeScreen.
expo-apple-authentication Known Used by AppleAuthenticationScreen.
expo-asset Known Used by AssetsScreen.
expo-av Known Used by AudioScreen.
expo-barcode-scanner Known Used by BarCodeScannerScreen.
expo-blur Known Used by BlurScreen.
expo-camera Known Used by CameraScreen.
expo-cli Ensure everybody has the same version.
expo-constants Known Used by the constants screens.
expo-facebook Known Used by FacebookScreen.
expo-font Known Used by FontScreen.
expo-linear-gradient Known Used by LinearGradientScreen.
expo-local-authentication Known Used by LocalAuthenticationScreen.
expo-sensors Known Used by accelerometer and gyroscope.
prettier File formatter.
react Known
react-native Known
react-native-gesture-handler Known TODO: Where is this used?
react-native-maps Known Used by MapsViewScreen.
react-native-reanimated Known TODO: Where is this used?
react-native-safe-area-context Known Use by react-navigation.
react-native-screens Known Used by react-navigation.
react-native-svg Known Used by SvgScreen.
typescript Known

Troubleshooting

If you have issues running the app it may help clearing the React Native packager cache. Use the command yarn expo start --clear to do this.

More tips found in this thread on the Expo Forum.

Automated Tests

This project hasn't been set up with automated tests. The blog post [setting up tests for React-Native-Expo-Typescript] can probably help.

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