RedwoodJS

# TypeScript

Redwood comes with full TypeScript support out of the box, and you don't have to give up any of the conveniences that Redwood offers to enjoy all the benefits of a type-safe codebase. You can use TypeScript and have great DX too.

# Starting a TypeScript Redwood project

You can use the --typescript flag on create-redwood-app to generate a project with TypeScript configured:

yarn create redwood-app --typescript my-redwood-app

# Converting an existing JS project to TypeScript

If you already have a Redwood app, but want to configure it for TypeScript, you can use our setup command:

yarn rw setup tsconfig

Remember you don't need to convert all your files to TypeScript, you can always do it incrementally. Start by renaming your files from .js to .ts or .tsx

Having issues with automatic setup? See instructions for manual setup below:

Manually setup TypeScript

This is what the setup command does for you step by step:

API

  1. Create a ./api/tsconfig.json file:
touch api/tsconfig.json

  1. Now copy and paste the latest config from the Redwood template api/tsconfig.json file here

WEB

  1. Create a ./api/tsconfig.json file:
touch web/tsconfig.json

  1. Now copy and paste the latest config from the Redwood template web/tsconfig.json file here

You should now have type definitions—you can rename your files from .js to .ts, and the files that contain JSX to .tsx.

# Sharing Types between sides

For your shared types, we need to do a few things:

  1. Put your shared types at the root of the project (makes sense right?), in a folder called types at the root
  2. Run 'Restart TS Server' in vscode via the command palette. And your new types should now be available on both web and api sides!

Redwood's tsconfig already contains the config for picking up types from web/types, api/types and types folders in your project.

If you have an outdated tsconfig, and would like to replace it (i.e. overwrite it), use the setup command with the force flag

yarn rw setup tsconfig --force

# Running type checks

Redwood uses Babel to transpile your TypeScript - which is why you are able to incrementally convert your project from JS to TS. However, it also means that just doing a build won't show you errors that the TypeScript compiler finds in your project

That's why we have the handy redwood type-check command!

To check your TypeScript project for errors, run

yarn rw type-check

This will run tsc on all the sides in your project, and make sure all the generated types are generated first, including Prisma.

# Check then build, on CI

Tip!
You don't need to build your project to run rw type-check

If your project is fully TypeScript, it might be useful to add typechecks before you run the deploy command in your CI.

For example, if you're deploying to Vercel, you could add a build:ci script to your package.json

"scripts": {
  .
  .
+  "build:ci": "yarn rw type-check && yarn rw test --no-watch && yarn rw deploy vercel",
}

Configure your project's build command to be yarn build:ci - and you even have your type checks and tests run whenever a pull request is opened!

# Auto generated types

Redwood's CLI automatically generates types for you, which not only includes types for your GraphQL queries, but also for your named routes, Cells, scenarios and tests.

When you run yarn rw dev, the CLI watches for file changes and automatically triggers the type generator.

To trigger type generation, you can run:

yarn rw g types

If you're curious, you can see the generated types in the .redwood/types folder, and in ./api/types/graphql.d.ts and ./web/types/graphql.d.ts in your project