Parcel (prcl)

0.4.0 verified Sat Apr 25 auth: no javascript

Parcel is an ultra-fast JavaScript bundler designed for development speed, v0.4.0, with no release cadence (sporadic). It avoids parsing JS fully, working mostly by concatenation with a few simple rules (no dynamic requires, no non-constant module names). Key differentiator: sub-10ms rebuilds, faster than Browserify or FuseBox by an order of magnitude, but lacks advanced features like tree-shaking. Ideal for rapid iteration during development, not production builds. ESM-only; CommonJS require() is used but only with static strings.

Common errors

error Error: Cannot find module 'prcl' ↓

cause Trying to import prcl programmatically, but it has no programmatic API.

fix

Use as CLI only: npx prcl index.js bundle.js

error Error: require is not defined ↓

cause Running bundled output in the browser without a module system.

fix

Parcel outputs CommonJS; in browser, load with a script tag but ensure require is defined (e.g., bundle with a shim). Or use for Node only.

error TypeError: Cannot read properties of undefined (reading 'map') ↓

cause Using a relative path require that doesn't resolve correctly; Parcel does not resolve Node modules from node_modules as robustly as other bundlers.

fix

Ensure all dependencies are installed and required with exact paths. For npm packages, use 'prcl' with explicit node_modules paths if needed.

Warnings

gotcha Package name is 'prcl' on npm, not 'parcel' (which is a different package). ↓

fix Install with `npm install -g prcl` or `npx prcl`. Do not confuse with `parcel`.

deprecated This package is extremely outdated (last release 2017?) and no longer maintained. Use at your own risk. ↓

fix Consider modern alternatives like esbuild or Vite for fast bundling.

gotcha Dynamic require() expressions are not supported; only static string literals. ↓

fix Replace dynamic requires with static ones or use a different bundler.

gotcha Variable or property named 'require' is forbidden. ↓

fix Rename any variable or property to avoid shadowing 'require'.

gotcha No tree-shaking; bundles entire modules even if you only use a small part. ↓

fix Use a production bundler like Webpack or Rollup for optimized output.

gotcha No built-in support for TypeScript, JSX, or CSS imports. ↓

fix Add transforms manually (e.g., tsc --module commonjs) before bundling.

gotcha Watch mode (-w) may have file descriptor leaks on some systems. ↓

fix Restart the process periodically or avoid long-running watch sessions.

Install

npm install prcl

yarn add prcl

pnpm add prcl

Imports

default (CLI)
wrong
```
npx parcel index.js bundle.js
```
correct
```
npx prcl index.js bundle.js
```
The npm package is 'prcl', not 'parcel'. The CLI command is 'prcl'.
N/A (no programmatic API)
wrong
```
import prcl from 'prcl'
```
correct
```
const prcl = require('prcl') // not exposed
```
Parcel has no documented programmatic API; it's purely a CLI tool.
CLI watch mode
wrong
```
prcl --watch index.js bundle.js
```
correct
```
prcl -w index.js bundle.js
```
Watch flag is '-w', not '--watch' (though both may work).

Quickstart

Basic usage: create two CommonJS modules, bundle with prcl via stdout redirection, run with Node.

// math.js
exports.square = x => x * x

// index.js
const itt = require('itt')
const math = require('./math')
console.log(itt.range(10).map(math.square).join(' '))

// terminal
// npm install -g prcl
// prcl index.js >bundle.js
// node bundle.js