Bun Quickstart Expert

Purpose

Expert guidance for getting started with Bun. Covers installation, project initialization, configuration, and quickstart guides for common use cases.

When to Use

Invoke this skill when:

• Installing Bun for the first time
• Creating new Bun projects
• Configuring bunfig.toml
• Setting up development environment
• Troubleshooting installation
• Learning Bun basics
• Scaffolding new projects with templates
• Understanding Bun's architecture

Documentation Available

Location:

/Users/zach/Documents/cc-skills/docs/bun/project/

+ root docs

Coverage (14 files):

• Installation (macOS, Linux, Windows)
• Upgrading Bun
• Project initialization (

  bun init

  )
• Configuration (bunfig.toml)
• Templates and scaffolding
• Development workflow
• Overview and concepts

Related Skills

• bun-runtime: After setup, for building applications
• bun-package-manager: For managing dependencies
• bun-test: For testing setup
• bun-bundler: For production builds

Installation

macOS and Linux

Using curl:

curl -fsSL https://bun.sh/install | bash

Using Homebrew (macOS):

brew install oven-sh/bun/bun

Verification:

bun --version

Windows

Using PowerShell:

powershell -c "irm bun.sh/install.ps1 | iex"

Using WSL:

# Install in WSL (Linux)
curl -fsSL https://bun.sh/install | bash

Docker

FROM oven/bun:1

WORKDIR /app

COPY package.json bun.lockb ./
RUN bun install

COPY . .

CMD ["bun", "run", "start"]

Upgrading Bun

# Upgrade to latest version
bun upgrade

# Upgrade to specific version
bun upgrade --version 1.0.0

# Upgrade to canary (nightly)
bun upgrade --canary

Project Initialization

Create New Project

# Interactive init
bun init

# With name
bun init my-app

# Skip prompts
bun init -y

Generated files:

my-app/
├── package.json
├── tsconfig.json
├── index.ts
└── README.md

Using Templates

# Create from template
bun create <template> <destination>

# React app
bun create react my-react-app

# Next.js app
bun create next my-next-app

# Vite app
bun create vite my-vite-app

# Express-like server
bun create hono my-api

Available templates:

• react

  - React with Vite

• next

  - Next.js

• vite

  - Vite

• hono

  - Hono server framework

• elysia

  - Elysia server framework

Configuration

bunfig.toml

Create

bunfig.toml

in project root or

~/.bun/bunfig.toml

globally:

# Install configuration
[install]
# Auto install peer dependencies
peer = true

# Production mode
production = false

# Registry
registry = "https://registry.npmjs.org"

# Cache directory
cache = "~/.bun/install/cache"

# Test configuration
[test]
# Preload files before tests
preload = ["./setup.ts"]

# Code coverage
coverage = true

# Default timeout
timeout = 5000

# Run configuration
[run]
# Shell for scripts
shell = "bash"

# Automatically install on bun run
autoInstall = true

Development Workflow

Running Files

# Run TypeScript directly
bun run index.ts

# Run with watch mode (hot reload)
bun --watch index.ts

# Run with environment variables
FOO=bar bun run index.ts

# Run from package.json script
bun run dev

REPL (Interactive Shell)

# Start REPL
bun

# In REPL:
> 2 + 2
4
> const data = await fetch("https://api.github.com").then(r => r.json())
> data

Package Scripts

package.json:

{
  "scripts": {
    "dev": "bun --watch src/index.ts",
    "build": "bun build src/index.ts --outdir dist --minify",
    "start": "bun dist/index.js",
    "test": "bun test",
    "lint": "eslint src"
  }
}

Run scripts:

bun run dev
bun run build
bun run start
bun test         # Shortcut (no "run" needed)

Environment Variables

.env File

# .env
DATABASE_URL=postgresql://localhost/mydb
API_KEY=secret123
NODE_ENV=development

Access in code:

// Bun-native (recommended)
const dbUrl = Bun.env.DATABASE_URL

// Node.js compatible
const apiKey = process.env.API_KEY

Load from different file:

bun --env-file=.env.production run index.ts

Quickstart Examples

Example 1: Simple HTTP Server

# Create project
bun init my-server
cd my-server

# Write server code
cat > index.ts << 'EOF'
const server = Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response("Hello from Bun!")
  },
})

console.log(`Server running at http://localhost:${server.port}`)
EOF

# Run server
bun --watch index.ts

Example 2: React App

# Create React app
bun create react my-react-app
cd my-react-app

# Install dependencies (if needed)
bun install

# Start dev server
bun run dev

Example 3: API with Database

# Create project
bun init my-api
cd my-api

# Install dependencies
bun add postgres

# Create database client
cat > db.ts << 'EOF'
import postgres from 'postgres'

export const sql = postgres(Bun.env.DATABASE_URL!)
EOF

# Create API
cat > index.ts << 'EOF'
import { sql } from './db'

const server = Bun.serve({
  port: 3000,
  async fetch(req) {
    const url = new URL(req.url)

    if (url.pathname === '/users') {
      const users = await sql`SELECT * FROM users`
      return Response.json(users)
    }

    return new Response('Not found', { status: 404 })
  },
})

console.log(`API running at http://localhost:${server.port}`)
EOF

# Run with .env
bun --watch index.ts

Common Commands

# Version
bun --version

# Help
bun --help

# Run file
bun run file.ts

# Install dependencies
bun install

# Add package
bun add react

# Remove package
bun remove react

# Run tests
bun test

# Build for production
bun build index.ts --outdir dist

# Create executable
bun build index.ts --compile --outfile myapp

# Upgrade Bun
bun upgrade

# REPL
bun

# Execute package
bun x cowsay "Hello!"

Troubleshooting

Installation Issues

macOS: "command not found: bun"

# Add to shell profile
echo 'export BUN_INSTALL="$HOME/.bun"' >> ~/.zshrc
echo 'export PATH="$BUN_INSTALL/bin:$PATH"' >> ~/.zshrc
source ~/.zshrc

Linux: Permission denied

# Give execute permission
chmod +x ~/.bun/bin/bun

Windows: Execution policy

# Allow script execution
Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

Common Errors

"Cannot find module"

# Install dependencies
bun install

# Or auto-install
bun run --install index.ts

"Port already in use"

# Find process using port
lsof -i :3000

# Kill process
kill -9 <PID>

Performance

Why Bun is fast:

• JavaScriptCore - Safari's JS engine (faster startup than V8)
• Zig - Built in Zig (low-level, fast)
• Native APIs - Optimized file I/O, HTTP, etc.
• No transpilation - Runs TypeScript natively

Benchmarks:

• 4x faster startup than Node.js
• 25x faster installs than npm
• 100x faster bundling than Webpack
• 20-40x faster tests than Jest

Search Helpers

# Find installation docs
grep -r "install\|setup" docs/bun/project/

# Find config docs
grep -r "bunfig\|config" docs/bun/project/

# Find init docs
grep -r "init\|create" docs/bun/project/

# List all quickstart docs
ls docs/bun/project/

Best Practices

1. Use TypeScript - Bun runs it natively, no config needed
2. Enable watch mode - Faster development with

   --watch

3. Use bunfig.toml - Centralized configuration
4. Leverage .env - Environment-specific config
5. Use bun create - Scaffolding with templates
6. Hot reload - Use

   --hot

   for instant updates
7. Profile performance - Use

   bun:jsc

   for profiling

Next Steps

After setup:

1. Build APIs → See bun-runtime skill
2. Write tests → See bun-test skill
3. Manage packages → See bun-package-manager skill
4. Bundle for production → See bun-bundler skill

Notes

• Documentation covers latest Bun version
• Bun is compatible with Node.js APIs
• TypeScript works out of the box
• File paths reference local documentation cache
• For latest updates, check https://bun.sh/docs