bun-router

A high-performance, feature-rich router for Bun applications.

Features

• Fast and efficient routing system
• Support for all HTTP methods
• Path parameters and parameter constraints
• Middleware support with built-in middleware
• Group routing, resource routing, and nested routes
• Named routes and URL generation
• Domain and subdomain routing
• CSRF protection and session management
• Type-safe API
• Native Bun.serve() integration
• WebSocket support

Installation

bun add bun-router

Basic Usage

import { Router } from 'bun-router'

// Create a router
const router = new Router()

// Define routes
router.get('/', () => new Response('Hello, World!'))
router.post('/users', async (req) => {
  const data = await req.json()
  return Response.json({ message: 'User created', data })
})

// Start the server
router.serve({
  port: 3000,
})

Route Options

// Route with path parameters
router.get('/users/{id}', (req) => {
  const { id } = req.params
  return Response.json({ id })
})

// Named routes
router.get('/users/{id}', getUserHandler, 'api', 'users.show')

// Generate URL for named route
const url = router.route('users.show', { id: '123' })

Middleware

import { cors, jsonBody, Router } from 'bun-router'

const router = new Router()

// Use middleware globally
router.use(jsonBody())
router.use(cors())

// Or apply to a group of routes
router.group({
  prefix: '/api',
  middleware: [jsonBody(), cors()]
}, () => {
  router.get('/users', () => Response.json({ users: [] }))
})

Built-in Middleware

• Cors - Handles Cross-Origin Resource Sharing
• JsonBody - Parses JSON request bodies into req.jsonBody
• RequestId - Adds unique IDs to requests with X-Request-ID header
• Session - Provides session management with req.session
• Csrf - Protects against cross-site request forgery
• Auth - Basic authentication middleware

Creating Custom Middleware

import { EnhancedRequest, MiddlewareHandler, NextFunction } from 'bun-router'

class LoggerMiddleware {
  async handle(req: EnhancedRequest, next: NextFunction): Promise<Response> {
    console.log(`${req.method} ${req.url}`)
    return next()
  }
}

// Use custom middleware
router.use(new LoggerMiddleware())

WebSocket Support

bun-router provides seamless integration with Bun's high-performance WebSocket capabilities:

import type { ServerWebSocket } from 'bun'
import { Router } from 'bun-router'

// Define data type for WebSocket clients
interface ClientData {
  userId: string
  room: string
}

// Create a router
const router = new Router<ClientData>() // Type-safe WebSockets

// Add a regular HTTP route
router.get('/', () => new Response('WebSocket Server'))

// Configure WebSocket handling
router.websocket({
  // Handle new connections
  open(ws) {
    console.log('Client connected from:', ws.remoteAddress)

    // Set client data (available in all handlers as ws.data)
    ws.data = { userId: 'user_123', room: 'general' }

    // Subscribe to topics for pub/sub messaging
    ws.subscribe('general')
    ws.send('Welcome to the server!')
  },

  // Handle incoming messages
  message(ws, message) {
    // Handle different message types (string, ArrayBuffer, Uint8Array)
    const content = typeof message === 'string' ? message : 'Binary data received'
    console.log(`Received from ${ws.data.userId}: ${content}`)

    // Send response and check for backpressure
    const sendResult = ws.send(`Echo: ${content}`)

    if (sendResult === -1) {
      console.log('Backpressure detected, message queued')
    }
    else if (sendResult === 0) {
      console.log('Send failed, connection may be closed')
    }
    else {
      console.log(`Sent ${sendResult} bytes`)
    }

    // Broadcast to all subscribers of a topic (except sender)
    router.publish('general', `${ws.data.userId}: ${content}`)
  },

  // Handle disconnections
  close(ws, code, reason) {
    console.log(`Client ${ws.data.userId} disconnected: ${reason || 'No reason'} (${code})`)
    ws.unsubscribe('general')
  },

  // Handle errors
  error(ws, error) {
    console.error(`Error for client ${ws.data.userId}:`, error)
  },

  // Handle backpressure relief
  drain(ws) {
    console.log(`Backpressure relieved for ${ws.data.userId}, socket ready for more data`)
  },

  // Advanced configuration options
  maxPayloadLength: 16 * 1024 * 1024, // 16MB max message size (default)
  idleTimeout: 120, // 2 minutes (default)
  backpressureLimit: 1024 * 1024, // 1MB (default)
  closeOnBackpressureLimit: false, // Don't close on backpressure limit (default)

  // Enable per-message compression
  perMessageDeflate: {
    compress: '16KB', // Use 16KB compression level
    decompress: true
  },

  sendPings: true, // Send ping frames to keep connection alive (default)
  publishToSelf: false // Don't send published messages to publisher (default)
})

// Start the server
router.serve({ port: 3000 })

WebSocket Utility Methods

The router provides utility methods for working with WebSockets:

// Publish a message to all subscribers of a topic
// Returns: Number of bytes sent (or negative on error)
const result = router.publish('room-123', JSON.stringify({
  type: 'message',
  text: 'Hello!'
}), true) // Optional: enable compression

// Get the number of subscribers for a topic
const count = router.subscriberCount('room-123')

// Upgrade an HTTP request to a WebSocket connection
router.get('/custom-upgrade', (req) => {
  const success = router.upgrade(req, {
    // Optional custom headers for the 101 Switching Protocols response
    headers: { 'X-Custom-Header': 'value' },

    // Custom data to attach to the WebSocket
    data: {
      userId: '123',
      authenticated: true,
      permissions: ['read', 'write']
    }
  })

  if (!success) {
    return new Response('Failed to upgrade connection', { status: 400 })
  }

  // If upgrade is successful, this response is ignored
  return new Response('Upgraded to WebSocket')
})

// Get client IP address
router.get('/ip', (req) => {
  const ip = router.requestIP(req)
  return Response.json(ip)
})

// Set custom timeout for a request
router.get('/long-operation', (req) => {
  // Extend timeout to 5 minutes for this specific request
  router.timeout(req, 300)

  // Perform long operation...
  return new Response('Operation completed')
})

WebSocket Patterns

Here are some common patterns for working with WebSockets:

JSON Communication

// Client-side
const ws = new WebSocket('ws://localhost:3000/ws')
ws.send(JSON.stringify({ type: 'login', userId: '123' }))

// Server-side
router.websocket({
  message(ws, message) {
    try {
      const data = JSON.parse(message.toString())

      switch (data.type) {
        case 'login':
          handleLogin(ws, data.userId)
          break
        case 'message':
          handleMessage(ws, data)
          break
      }
    }
    catch (e) {
      ws.send(JSON.stringify({ error: 'Invalid JSON' }))
    }
  }
})

Room-Based Chat

router.websocket({
  open(ws) {
    ws.data = { userId: generateId(), room: 'lobby' }
    ws.subscribe('lobby')
    broadcastToRoom('lobby', `${ws.data.userId} joined the lobby`)
  },

  message(ws, message) {
    const text = message.toString()

    if (text.startsWith('/join ')) {
      const newRoom = text.slice(6).trim()

      // Leave current room
      const oldRoom = ws.data.room
      ws.unsubscribe(oldRoom)
      broadcastToRoom(oldRoom, `${ws.data.userId} left the room`)

      // Join new room
      ws.data.room = newRoom
      ws.subscribe(newRoom)
      broadcastToRoom(newRoom, `${ws.data.userId} joined the room`)

      ws.send(`You joined ${newRoom}`)
    }
    else {
      // Regular message
      broadcastToRoom(ws.data.room, `${ws.data.userId}: ${text}`)
    }
  }
})

function broadcastToRoom(room, message) {
  router.publish(room, message)
}

Handling Backpressure

router.websocket({
  message(ws, message) {
    // Send a large response
    const largeData = generateLargeResponse()
    const result = ws.send(largeData)

    if (result === -1) {
      // Message was queued due to backpressure
      console.log('Backpressure detected, will process more in drain event')

      // Store state to resume in drain handler
      ws.data.pendingOperations = [/* ...operations to complete */]
    }
  },

  drain(ws) {
    // Socket is ready to receive more data
    if (ws.data.pendingOperations?.length) {
      const nextOp = ws.data.pendingOperations.shift()
      processOperation(ws, nextOp)
    }
  }
})

Bun-Native Features

bun-router fully integrates with Bun's native Bun.serve() API, leveraging the latest Bun features for optimal performance.

Static Responses

Define static routes without handler functions for optimal performance:

router.get('/health', () => new Response('OK'))
router.get('/ready', () => new Response('Ready', {
  headers: { 'X-Ready': '1' }
}))

// These are automatically optimized to Bun's static routes internally

Method-Specific Handlers

The router automatically organizes multiple methods for the same path into Bun's method-specific handlers:

router.get('/api/posts', getPosts)
router.post('/api/posts', createPost)
router.put('/api/posts/{id}', updatePost)
router.delete('/api/posts/{id}', deletePost)

// These will be organized into a more efficient format:
// '/api/posts': {
//   GET: getPosts,
//   POST: createPost
// },
// '/api/posts/{id}': {
//   PUT: updatePost,
//   DELETE: deletePost
// }

Hot Reloading

Update routes without restarting the server:

// Initial setup
const router = new Router()
router.get('/api/version', () => Response.json({ version: '1.0.0' }))
const server = await router.serve({ port: 3000 })

// Later, update routes without downtime
router.get('/api/version', () => Response.json({ version: '2.0.0' }))
await router.reload()

Error Handling

Add a global error handler for all routes:

router.onError((error) => {
  console.error(error)
  return new Response(`Server Error: ${error.message}`, {
    status: 500,
    headers: { 'Content-Type': 'text/plain' }
  })
})

// Define a route that might throw an error
router.get('/api/risky', () => {
  throw new Error('Something went wrong')
})

// Serve with the error handler
router.serve({ port: 3000 })

Type-Safe Route Parameters

TypeScript automatically infers parameter types from route paths:

router.get('/orgs/{orgId}/repos/{repoId}', (req) => {
  // TypeScript knows the shape of req.params
  const { orgId, repoId } = req.params
  return Response.json({ orgId, repoId })
})

Cookie Handling

Built-in support for working with cookies:

router.get('/profile', (req) => {
  // Read cookies
  const userId = req.cookies.get('user_id')
  const theme = req.cookies.get('theme') || 'light'

  return Response.json({ userId, theme })
})

router.get('/login', (req) => {
  // Set cookies
  req.cookies.set('user_id', '12345', {
    httpOnly: true,
    secure: true,
    maxAge: 60 * 60 * 24 // 1 day
  })

  return new Response('Logged in')
})

router.get('/logout', (req) => {
  // Delete cookies
  req.cookies.delete('user_id')
  return new Response('Logged out')
})

Authentication Helper

Built-in methods for handling various authentication strategies:

// Basic Authentication
router.get('/api/protected', (req) => {
  const auth = req.auth.basic()

  if (!auth.isValid()) {
    return auth.unauthorized('Protected area')
  }

  const { username, password } = auth.credentials()
  // Verify against your user database

  return Response.json({ message: 'Authenticated' })
})

// Bearer Token Authentication
router.get('/api/user-profile', (req) => {
  const auth = req.auth.bearer()

  if (!auth.isValid()) {
    return auth.unauthorized('Invalid token')
  }

  const token = auth.token()
  // Verify token validity

  return Response.json({ message: 'Valid token' })
})

// JWT Authentication
router.post('/api/login', async (req) => {
  const { username, password } = await req.json()
  // Verify credentials

  const auth = req.auth.jwt()
  const token = auth.sign({ userId: 123, role: 'admin' }, {
    expiresIn: '1h',
    secret: 'your-secret-key'
  })

  return Response.json({ token })
})

router.get('/api/dashboard', (req) => {
  const auth = req.auth.jwt()

  if (!auth.verify({ secret: 'your-secret-key' })) {
    return auth.unauthorized('Invalid JWT')
  }

  const payload = auth.payload()
  return Response.json({ user: payload })
})

// API Key Authentication
router.get('/api/data', (req) => {
  const auth = req.auth.apiKey('x-api-key')

  if (!auth.isValid()) {
    return auth.unauthorized('Invalid API key')
  }

  const apiKey = auth.key()
  // Verify API key against database and check scopes

  return Response.json({ data: 'Secure data' })
})

// OAuth2 Authentication
router.get('/auth/github', (req) => {
  const auth = req.auth.oauth2({
    provider: 'github',
    clientId: 'your-client-id',
    redirectUri: 'http://localhost:3000/auth/callback'
  })

  return auth.redirect()
})

router.get('/auth/callback', async (req) => {
  const auth = req.auth.oauth2({
    provider: 'github',
    clientId: 'your-client-id',
    clientSecret: 'your-client-secret',
    redirectUri: 'http://localhost:3000/auth/callback'
  })

  const { accessToken, profile } = await auth.handleCallback(req)
  // Create or update user record

  return Response.redirect('/dashboard')
})

### File Streaming

Easily stream files with range support:

```typescript
router.get('/files/{filename}', async (req) => {
  const filename = req.params.filename
  const path = `./uploads/${filename}`

  // Simple file streaming
  return router.streamFile(path, {
    headers: {
      'Content-Type': 'application/octet-stream',
      'Content-Disposition': `attachment; filename="${filename}"`
    }
  })
})

// With range support for video/audio streaming
router.get('/videos/{id}', async (req) => {
  const videoPath = `./videos/${req.params.id}.mp4`
  return router.streamFileWithRanges(videoPath, req)
})

Route Groups

router.group({
  prefix: '/api',
  middleware: [jsonBody()]
}, () => {
  router.get('/users', getUsersHandler)
  router.post('/users', createUserHandler)
})

Parameter Constraints

router.get('/users/{id}', getUserHandler)
  .whereNumber('id')

router.get('/categories/{slug}', getCategoryHandler)
  .whereAlpha('slug')

// Available constraints
router.whereNumber('id')
router.whereAlpha('name')
router.whereAlphaNumeric('username')
router.whereUuid('id')
router.whereIn('status', ['active', 'pending'])

RESTful Resources

// Creates all RESTful routes for 'posts'
router.resource('posts', 'PostsController')

// Equivalent to:
router.get('/posts', 'PostsController/index')
router.get('/posts/{id}', 'PostsController/show')
router.post('/posts', 'PostsController/store')
router.put('/posts/{id}', 'PostsController/update')
router.delete('/posts/{id}', 'PostsController/destroy')

Redirects

router.redirectRoute('/old-path', '/new-path')
router.permanentRedirectRoute('/very-old-path', '/new-path')

Domain Routing

router.domain('{account}.example.com', () => {
  router.get('/', (req) => {
    const account = req.params.account
    return new Response(`Welcome to ${account}'s subdomain!`)
  })
})

Configuration

const router = new Router({
  verbose: true,
  apiPrefix: '/api/v1',
  defaultMiddleware: {
    api: ['Middleware/Cors', 'Middleware/JsonBody'],
    web: ['Middleware/Session', 'Middleware/Csrf']
  }
})

Changelog

Please see our releases page for more information on what has changed recently.

Contributing

Please see CONTRIBUTING for details.

Community

For help, discussion about best practices, or any other conversation that would benefit from being searchable:

Discussions on GitHub

For casual chit-chat with others using this package:

Join the Stacks Discord Server

Postcardware

"Software that is free, but hopes for a postcard." We love receiving postcards from around the world showing where Stacks is being used! We showcase them on our website too.

Our address: Stacks.js, 12665 Village Ln #2306, Playa Vista, CA 90094, United States 🌎

Sponsors

We would like to extend our thanks to the following sponsors for funding Stacks development. If you are interested in becoming a sponsor, please reach out to us.

• JetBrains
• The Solana Foundation

License

The MIT License (MIT). Please see LICENSE for more information.

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