CLI Interface

# Build command (default) - Build once and exit
microbundle [entries...] [options]
microbundle build [entries...] [options]

# Watch command - Rebuilds on any source file change
microbundle watch [entries...] [options]

# Basic build using package.json configuration
microbundle

# Build specific entry files
microbundle src/index.js src/cli.js

# Build with custom output formats
microbundle --format esm,cjs,umd

# Development mode with watch
microbundle watch --sourcemap

# Node.js library build
microbundle --target node --format cjs --no-compress

# Custom output directory
microbundle --output dist/bundle.js

# Build with external dependencies
microbundle --external react,lodash --globals react=React,lodash=_

# Entry and Output Options
--entry, -i, -e <files>       # Entry module(s) (comma-separated or multiple flags)
--output, -o, -d <path>       # Directory or file path for build output

# Format and Target Options  
--format, -f <formats>        # Output formats: modern,esm,cjs,umd,iife (default: modern,esm,cjs,umd)*
--target <env>                # Target environment: web or node (default: web)

# * Default format includes 'modern' unless MICROBUNDLE_MODERN=false environment variable is set

# Dependency Options
--external <deps>             # External dependencies (comma-separated) or 'none'
--globals <mappings>          # Global variable mappings for UMD (e.g., react=React,jquery=$)

# Optimization Options
--compress                    # Enable Terser compression (default: true for web, false for node)
--no-compress                 # Disable compression explicitly
--strict                      # Enforce undefined global context and "use strict"

# Development Options
--watch, -w                   # Enable watch mode (rebuild on changes)
--sourcemap                   # Generate source maps (default: true)
--no-sourcemap                # Disable source maps
--raw                         # Show raw byte sizes instead of gzipped

# Build Customization
--define <definitions>        # Replace constants (e.g., API_KEY=1234,@assign=Object.assign)
--alias <mappings>            # Module import aliases (e.g., react=preact/compat)
--name <globalName>           # Global name for UMD builds
--cwd <directory>             # Working directory (default: current directory)

# TypeScript Options
--tsconfig <path>             # Path to custom TypeScript configuration
--generateTypes               # Generate TypeScript declaration files
--no-generateTypes            # Disable TypeScript declaration generation

# Styling Options
--css <mode>                  # CSS output mode: inline or external (default: external)
--css-modules <config>        # CSS modules configuration

# Advanced Options
--workers                     # Bundle web workers using off-main-thread
--visualize                   # Generate bundle composition visualization (stats.html)
--pkg-main                    # Use package.json main entries for output paths (default: true)
--no-pkg-main                 # Disable package.json main entry usage

# JSX Options
--jsx <pragma>                # JSX pragma function (default: h)
--jsxFragment <pragma>        # JSX fragment pragma (default: Fragment)  
--jsxImportSource <source>    # JSX import source for automatic runtime

# Help and Version
--version, -v                 # Display version number
--help, -h                    # Display help information

{
  "name": "my-library",
  "source": "src/index.js",
  "main": "dist/index.js",
  "module": "dist/index.esm.js",
  "unpkg": "dist/index.umd.js",
  "types": "dist/index.d.ts",
  "scripts": {
    "build": "microbundle",
    "dev": "microbundle watch"
  },
  "files": ["dist", "src"]
}

# Control modern format inclusion
MICROBUNDLE_MODERN=false microbundle  # Disables modern format, uses only esm,cjs,umd
MICROBUNDLE_MODERN=true microbundle   # Enables modern format (default behavior)

# Set compression based on NODE_ENV (overrides target-specific defaults)
NODE_ENV=production microbundle   # Enables compression regardless of target
NODE_ENV=development microbundle  # Disables compression for faster builds

# Example: Development build with specific format
MICROBUNDLE_MODERN=false NODE_ENV=development microbundle --format esm,cjs

# Modern format - optimized for modern browsers supporting ES modules
--format modern
# Outputs: *.modern.js - Preserves modern syntax, smaller bundles

# ECMAScript Modules - standard import/export syntax
--format esm  
# Outputs: *.esm.js or *.module.js - For bundlers and modern Node.js

# CommonJS - Node.js require/module.exports  
--format cjs
# Outputs: *.js or *.cjs - For Node.js and older bundlers

# Universal Module Definition - works everywhere
--format umd
# Outputs: *.umd.js - For browser globals, AMD, and CommonJS

# Immediately Invoked Function Expression - direct browser usage
--format iife
# Outputs: *.iife.js - Self-executing bundle for browser script tags

# Build multiple entry points
microbundle src/index.js src/cli.js src/worker.js

# Using glob patterns (via package.json source field)
# package.json: "source": "src/*.js"
microbundle

# Library for browsers and Node.js
microbundle --format modern,esm,cjs --target web
microbundle src/node.js --format cjs --target node --output dist/node.js

# Development build with debugging
microbundle watch --sourcemap inline --no-compress --format esm

# Production build with optimization
microbundle --compress --no-sourcemap --visualize --format modern,esm,cjs,umd

# Basic TypeScript build
microbundle src/index.ts --generateTypes

# Custom TypeScript configuration  
microbundle --tsconfig tsconfig.build.json --generateTypes

# Mixed JavaScript and TypeScript
microbundle src/index.js src/types.ts --generateTypes

# React components with custom JSX pragma
microbundle --jsx React.createElement --jsxFragment React.Fragment

# Preact components
microbundle --jsx h --jsxFragment Fragment

# Modern automatic JSX runtime
microbundle --jsxImportSource react

# Missing entry file
Error: No entry module found
# Solution: Specify --entry or add "source" field to package.json

# Unresolved dependencies  
Error: Could not resolve 'react'
# Solution: Add to --external or install as dependency

# TypeScript configuration issues
Error: TypeScript compilation failed
# Solution: Check --tsconfig path or fix TypeScript errors

# Permission issues
Error: EACCES: permission denied
# Solution: Check file permissions or use sudo (not recommended)

# Enable tab completion (if supported by your shell)
eval "$(microbundle --completion)"

{
  "scripts": {
    "build": "microbundle",
    "build:prod": "microbundle --compress --no-sourcemap",  
    "build:dev": "microbundle --no-compress --sourcemap inline",
    "dev": "microbundle watch",
    "dev:node": "microbundle watch --target node --format cjs",
    "analyze": "microbundle --visualize",
    "type-check": "microbundle --generateTypes --no-compress"
  }
}

# Continuous Integration
npm run build
# or
npx microbundle --format modern,esm,cjs,umd --compress

# Pre-commit hooks
microbundle --format esm,cjs --no-compress --sourcemap