Parcel

Language: JavaScript

Build Tool / Bundler

Parcel was created by Devon Govett to provide an easier and faster alternative to Webpack. It focuses on simplicity and speed, using worker processes for parallel compilation, automatic dependency resolution, and built-in support for modern web standards.

Parcel is a fast, zero-configuration web application bundler. It supports JavaScript, TypeScript, CSS, HTML, images, and more out of the box without requiring a complex configuration.

Installation

npm: npm install --save-dev parcel

yarn: yarn add --dev parcel

pnpm: pnpm add --save-dev parcel

Usage

Parcel automatically detects the entry point of your project and builds an optimized bundle. It supports hot module replacement, code splitting, tree-shaking, and integrates well with modern frontend frameworks like React, Vue, and Svelte.

Simple build and dev server

# package.json scripts
"scripts": {
  "start": "parcel index.html",
  "build": "parcel build index.html"
}

# Run dev server
npm run start
# Build for production
npm run build

Starts a development server with HMR and builds a production bundle for deployment.

Using with JavaScript modules

// src/index.js
import { greet } from './greet.js';
greet();

// src/greet.js
export function greet() { console.log('Hello, Parcel!'); }

Parcel automatically bundles JavaScript modules without requiring configuration.

React setup

# src/index.jsx
import React from 'react';
import ReactDOM from 'react-dom';
import App from './App.jsx';
ReactDOM.render(<App />, document.getElementById('root'));

Parcel supports JSX out of the box and can bundle React applications with zero configuration.

CSS and asset handling

// index.js
import './style.css';
import logo from './logo.png';
document.body.appendChild(Object.assign(new Image(), { src: logo }));

Parcel processes CSS, images, and other assets automatically during bundling.

Environment variables

process.env.NODE_ENV // Access environment variables defined in .env files

Parcel automatically loads `.env` files and exposes variables to your code.

Code splitting

// Dynamic import
import('./module.js').then(module => { module.doSomething(); });

Parcel automatically splits dynamically imported modules into separate bundles.

Error Handling

Cannot find module: Ensure all dependencies are installed and paths are correct.

Unexpected token: Check that file types are supported or install required Parcel plugins (e.g., for TypeScript or JSX).

Port already in use: Change the development server port using `parcel index.html --port 3001`.

Best Practices

Use `.env` files to manage environment-specific settings.

Organize source files in a clear folder structure for maintainability.

Leverage Parcel plugins if you need additional functionality like TypeScript or PostCSS.

Use dynamic imports for code splitting and faster page load.

Monitor build output to ensure bundle size is optimized.

Official Docs Github