How to Setup React App with Parcel and TypeScript

Parcel is a zero-config build tool with great out-of-the-box development experience and scalable architecture.

I experimented with Parcel in my previous project and I am happy with the result. (The second project of the Front End Development Libraries Curriculum of FreeCodeCamp.)

The setup process was a bit difficult. Thus, I will guide you to simplify this process in this article.

Note: To access the completed boilerplate, you can visit the react-parcel-ts-boilerplate.

1. Installing Dependencies

I have used npm for this boilerplate. But feel free to use any package manager you choose.

First, you need to install react and react-dom as dependencies.

npm i react react-dom

Next, you need parcel and typescript packages as development dependencies, also since this is a TypeScript project, you need type definitions for react and react-dom.

npm i -D parcel typescript @types/react @types/react-dom

2. Configuring `tsconfig.json`

The documentation says that:

Parcel supports TypeScript out of the box without any additional configuration.

When you try to run or build the app there is no problem. Yet, I consistently encountered TypeScript errors with IntelliSense.

Screenshot showing the error message: 'Cannot use JSX unless the --jsx flag is provided'.

In order to address these issues, I recommend using the following tsconfig.json file, as this configuration helped me resolve those issues:

{
  "compilerOptions": {
    "module": "ESNext",
    "target": "ESNext",
    "moduleResolution": "node",
    "lib": ["DOM", "ESNext"],
    "jsx": "react-jsx"
  }
}

3. Creating Base Files

You need to create these three files in the src directory:

1. App.tsx: This file serves as the root component of the app.

const App = () => <div>App</div>;

export { App };

2. index.tsx: This file is responsible for rendering the App component into the <div id="app"> element on the page.

import { createRoot } from 'react-dom/client';
import { App } from './App';

const root = createRoot(document.getElementById('app') as HTMLElement);

root.render(<App />);

3. index.html: This file serves as the entry point for the app.

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>React (Parcel + TypeScript)</title>
  </head>
  <body>
    <div id="app"></div>
    <script type="module" src="index.tsx"></script>
  </body>
</html>

4. Configuring `package.json`

Make sure to add the source property in the package.json (No need for the main property.), and set its value as the path to the index.html file.

"source": "src/index.html"

Additionally, in order to run the app using scripts, you need to add the necessary scripts to the package.json file.

"scripts": {
  "start": "parcel",
  "build": "parcel build"
}

5. Running the App

Since the app is ready, you can run it with start script:

npm start

The "failed to install modules" Error

You may come across the following error, which I encountered when using pnpm in my previous project:

Screenshot showing the error message: 'Failed to install process: pnpm failed to install modules'.

To resolve this issue, add the process property under the alias property in the package.json file and set its value to false.

"alias": {
  "process": false
}

Conclusion

Developing a React project with Parcel and TypeScript can present challenges, particularly on the TypeScript side. However, using this boilerplate was beneficial in my previous project, and I believe it can assist you as well.

Thank you for reading. Feel free to share your thoughts about Parcel in the comments section.

See you in the next one!

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Resources

Parcel Documentation