Installation

Requirements:

• rescript@11.0 or later

• react@18.0.0 or later

Add the following dependency to your ReScript project (in case you don't have any project yet, check out the installation instructions):

npm install @rescript/react

Then add the following setting to your existing rescript.json:

JSON
{
  "jsx": { "version": 4 },
  "bs-dependencies": ["@rescript/react"]
}

Note: In case your dependencies are not compatible with version 4 of the ReScript JSX transformation yet, you can use v3 in the same project. Check out the details in Migrate from v3.

To test your setup, create a new .res file in your source directory and add the following code:

RES
// src/Test.res
@react.component
let make = () => {
  <div> {React.string("Hello World")} </div>
}

Now run npx rescript and you should see a successful build.

Exposed Modules

After a successful installation, @rescript/react will make the following modules available in your project's global scope:

• React: Bindings to React

• ReactDOM: Bindings to the ReactDOM

• ReactDOMServer: Bindings to the ReactDOMServer

• ReactEvent: Bindings to React's synthetic events

• ReactDOMStyle: Bindings to the inline style API

• RescriptReactRouter: A simple, yet fully featured router with minimal memory allocations

• RescriptReactErrorBoundary: A component which handles errors thrown in its child components gracefully

Automatic vs. Classic Mode

By default, JSX v4 uses the new JSX runtime (react/jsx-runtime) introduced in React 17. This is called "automatic mode", and can also be specified explicitly like this:

JSON
{
  "jsx": { "version": 4, "mode": "automatic" }
}

To keep using the legacy React.createElement API (like with JSX v3), you can activate classic mode instead:

JSON
{
  "jsx": { "version": 4, "mode": "classic" }
}