Bun Project Initialization

You are assisting with initializing a new Bun project. Follow these steps to create a well-structured project with optimal configurations.

Workflow

1. Check Prerequisites

First, verify Bun is installed:

bash

bun --version

If Bun is not installed, provide installation instructions for the user's platform.

2. Determine Project Type

Ask the user which type of project they want to create:

•CLI Tool: Command-line application with bin entry point
•Web App: Frontend application with React/Vue/etc
•API Server: Backend API with routing framework
•Library: Reusable package for publishing to npm

3. Run Bun Init

Execute the initialization command:

bash

bun init -y

This creates:

•package.json with Bun-optimized scripts
•tsconfig.json with recommended TypeScript settings
•index.ts as the entry point
•README.md with basic project info

4. Enhance TypeScript Configuration

Read the generated tsconfig.json and enhance it based on project type:

For CLI Tools:

json

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "types": ["bun-types"],
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "resolveJsonModule": true,
    "allowImportingTsExtensions": true,
    "noEmit": true
  }
}

For Web Apps:

json

{
  "compilerOptions": {
    "target": "ES2022",
    "lib": ["ES2022", "DOM", "DOM.Iterable"],
    "module": "ESNext",
    "moduleResolution": "bundler",
    "jsx": "react-jsx",
    "types": ["bun-types"],
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "resolveJsonModule": true,
    "allowImportingTsExtensions": true,
    "noEmit": true
  }
}

For API Servers:

json

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "types": ["bun-types"],
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "resolveJsonModule": true,
    "allowImportingTsExtensions": true,
    "noEmit": true,
    "paths": {
      "@/*": ["./src/*"]
    }
  }
}

For Libraries:

json

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "types": ["bun-types"],
    "strict": true,
    "declaration": true,
    "declarationMap": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "resolveJsonModule": true,
    "allowImportingTsExtensions": true,
    "noEmit": true
  }
}

5. Create Project Structure

Generate appropriate directory structure and files:

CLI Tool:

code

project/
├── src/
│   ├── index.ts          # Main CLI entry point
│   ├── commands/         # Command handlers
│   └── utils/            # Shared utilities
├── tests/
│   └── index.test.ts
├── package.json
├── tsconfig.json
├── .gitignore
├── .env.example
└── README.md

Create src/index.ts:

typescript

#!/usr/bin/env bun

console.log("Hello from Bun CLI!");

// Example: Parse command line arguments
const args = process.argv.slice(2);
console.log("Arguments:", args);

Update package.json to add bin field:

json

{
  "bin": {
    "your-cli-name": "./src/index.ts"
  }
}

Web App:

code

project/
├── src/
│   ├── index.tsx         # App entry point
│   ├── components/       # React components
│   ├── styles/           # CSS/styles
│   └── utils/            # Utilities
├── public/
│   └── index.html
├── tests/
├── package.json
├── tsconfig.json
├── .gitignore
├── .env.example
└── README.md

API Server:

code

project/
├── src/
│   ├── index.ts          # Server entry point
│   ├── routes/           # Route handlers
│   ├── middleware/       # Express/Hono middleware
│   ├── services/         # Business logic
│   └── types/            # TypeScript types
├── tests/
├── package.json
├── tsconfig.json
├── .gitignore
├── .env.example
└── README.md

Create src/index.ts:

typescript

const server = Bun.serve({
  port: 3000,
  fetch(request) {
    return new Response("Welcome to Bun!");
  },
});

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

Library:

code

project/
├── src/
│   ├── index.ts          # Main export
│   └── types.ts          # Type definitions
├── tests/
├── package.json
├── tsconfig.json
├── .gitignore
└── README.md

6. Create .gitignore

Generate a comprehensive .gitignore:

gitignore

# Bun
node_modules
bun.lockb
*.bun

# Environment
.env
.env.local
.env.*.local

# Build outputs
dist/
build/
*.tsbuildinfo

# Logs
logs
*.log
npm-debug.log*

# OS
.DS_Store
Thumbs.db

# IDE
.vscode/
.idea/
*.swp
*.swo
*~

# Test coverage
coverage/
.nyc_output/

7. Create Environment Template

Create .env.example:

bash

# Application
NODE_ENV=development
PORT=3000

# Add your environment variables here
# DATABASE_URL=
# API_KEY=

8. Update package.json Scripts

Add project-type-specific scripts:

CLI Tool:

json

{
  "scripts": {
    "dev": "bun run src/index.ts",
    "test": "bun test",
    "lint": "bun run --bun eslint src",
    "typecheck": "bun run --bun tsc --noEmit"
  }
}

Web App:

json

{
  "scripts": {
    "dev": "bun run --hot src/index.tsx",
    "build": "bun build src/index.tsx --outdir=dist --minify",
    "test": "bun test",
    "typecheck": "bun run --bun tsc --noEmit"
  }
}

API Server:

json

{
  "scripts": {
    "dev": "bun run --hot src/index.ts",
    "start": "bun run src/index.ts",
    "test": "bun test",
    "typecheck": "bun run --bun tsc --noEmit"
  }
}

Library:

json

{
  "scripts": {
    "build": "bun build src/index.ts --outdir=dist --minify --sourcemap=external",
    "test": "bun test",
    "typecheck": "bun run --bun tsc --noEmit",
    "prepublishOnly": "bun run build && bun test"
  }
}

9. Install Common Dependencies

Suggest installing common dependencies based on project type:

CLI Tool:

bash

bun add commander chalk ora
bun add -d @types/node

Web App:

bash

bun add react react-dom
bun add -d @types/react @types/react-dom

API Server:

bash

bun add hono
bun add -d @types/node

Library:

bash

# No default dependencies - user will add as needed

10. Create Initial Test File

Create a basic test file in tests/:

typescript

import { describe, expect, test } from "bun:test";

describe("Initial test", () => {
  test("basic assertion", () => {
    expect(1 + 1).toBe(2);
  });
});

Post-Initialization Checklist

After completing the setup, provide the user with:

•✅ Confirmation of project type created
•✅ List of generated files and directories
•
✅ Next steps:
- •Copy .env.example to .env and configure
- •Run bun install if dependencies were suggested
- •Run bun dev to start development
- •Run bun test to verify tests work

Key Configuration Principles

•Module Resolution: Use "moduleResolution": "bundler" for Bun's native resolution
•TypeScript Types: Always include "types": ["bun-types"]
•No Emit: Set "noEmit": true since Bun runs TypeScript directly
•Import Extensions: Enable "allowImportingTsExtensions": true for .ts imports
•Strict Mode: Enable strict TypeScript checks for better code quality

Common Adjustments

If user wants workspaces (monorepo):

Add to package.json:

json

{
  "workspaces": ["packages/*"]
}

If user wants path aliases:

Add to tsconfig.json:

json

{
  "compilerOptions": {
    "paths": {
      "@/*": ["./src/*"],
      "@components/*": ["./src/components/*"]
    }
  }
}

If user wants JSX without React:

Update tsconfig.json:

json

{
  "compilerOptions": {
    "jsx": "react-jsx",
    "jsxImportSource": "preact" // or other JSX runtime
  }
}

Completion

Once all files are created, inform the user that initialization is complete and provide a summary of:

•Project structure
•Available npm scripts
•Recommended next steps
•Links to Bun documentation for their project type