ts-migrate is a Node.js tools to convert from JavaScript to TypeScript.

We can easy to migrate your React application written by JavaScript to use it.

Prepare

In Create React App, we need to get the following files to use TypeScript.

• tsconfig.json
• src/react-app-env.d.ts

We can easy to get creating a new dummy React app.

$ npx create-react-app test --typescript
$ mv test/tsconfig.json ./
$ mv test/src/react-app-env.d.ts ./src

Installing npm packages for TypeScript

At least, we need add these packages.

$ npm i -D @types/react @types/react-dom @types/node @types/jest typescript

Run ts-migrate

Using ts-migrate, we can rename all js/jsx files to ts/tsx.

$ npx ts-migrate rename ./

And update all code to be able to run in TypeScript.

$ npx ts-migrate migrate ./

Fix errors of TypeScript

Depends on any dev tools like prop-types, sometimes, ts-migrate will remain any TS errors.

We should run npm run build and fix all errors.