TS United: Metro (React Native) Edition

Building shared code and reinstalling it into all parts of a monorepo (backend, frontend, mobile)? Incrementing version and publishing shared code to NPM on every small change? Wasting time? Forget about it with TS United!

TS United helps one TypeScript project (folder containing a tsconfig.json file) import TypeScript/JavaScript code from any other project, while checking each project's code and resolving imports in each project using that project's tsconfig.json.

Note: Metro Edition is compatible with Metro bundler's runtime (used in React Native). If you're using another runtime, go to the list of editions and choose the edition you need.

Metro Edition provides a resolver that allows Metro to import Typescript/JavaScript code from other projects.

Sounds great? Let's get started!

Adding TS United to your React Native project

Step one: Install the @ts-united/metro package from NPM into your main (aka root) project. Root project is the project you'll run npm start in when starting the whole app. For example, the mobile part of your app will be a root project.

Step two: Create a TS United config object inside your metro.config.js like this:

const TS_UNITED_CONFIG = {
    // ...config
};

module.exports = {
    // ...metro config
};

See the Config options section below for complete explanation of config options. It also shows an example config.

Step three: Register TS United resolver in Metro config file.

const { UnitedMetroResolver } = require("@ts-united/metro");

const TS_UNITED_CONFIG = {
    // ...config
};

const unitedResolver = new UnitedMetroResolver(TS_UNITED_CONFIG);

module.exports = {
    // ...metro config
    watchFolders: unitedResolver.watchFolders,
    resolver: {
        resolveRequest: unitedResolver.resolver,
    },
};

That's all! Now your project uses TS United! Import files from other projects and then run npm run android and npm run ios as usual.

Tip: Any project can import any other project, listed in config file. Related projects can import each other and can import root project (importing root project from related projects is not recommended).

Also you can see a complete example project on GitHub: https://github.com/R-Mielamud/TsUnited/tree/main/example/react-native-mobile

Config options

| Option | Data type | Default value | Description | | ----------------- | ---------------------------- | --------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | | cwd | string(path)? | process.cwd() | CWD is a base directory for all other directories in config. It can be either absolute or relative. If it's relative, it'll be relative to process.cwd(). | | rootProject | Project | | Root project's info (see Project schema below). | | relatedProjects | Array<Project>? | [] | Array containing related projects' info. If empty, no projects will be considered related. |

Project schema

| Option | Data type | Default value | Description | | ------ | ---------------- | ------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | name | string, unique | | Any unique project name (id). | | path | string(path) | | The path tsconfig.json file is located in or any child path. Importing files that are outside all projects' paths is forbidden. The path can be absolute or relative to CWD. |

Example folder structure and config:

|---myproject
    |---shared
        |--- ...
        |---tsconfig.json
    |---mobile - the root project
        |--- ...
        |---metro.config.js
        |---tsconfig.json
    |---tsconfig.base.json

// /myproject/mobile/metro.config.js

const TS_UNITED_CONFIG = {
    cwd: "../", // /myproject
    rootProject: {
        name: "mobile",
        path: "./mobile", // /myproject/mobile
    },
    relatedProjects: [
        {
            name: "shared",
            path: "./shared", // /myproject/shared
        },
    ],
};

module.exports = {
    // ...metro config
};