Bun

Bun is another JavaScript runtime. It's not Node.js or Deno. Bun includes a trans compiler, we can write the code with TypeScript. Hono also works on Bun.

1. Install Bun

To install bun command, follow the instruction in the official web site.

2. Setup

A starter for Bun is available. Start your project with "bun create" command. Select bun template for this example.

bun create hono my-app

Move into my-app and install the dependencies.

cd my-app
bun install

3. Hello World

"Hello World" script is below. Almost the same as writing on other platforms.

import { Hono } from 'hono'

const app = new Hono()
app.get('/', (c) => c.text('Hello Bun!'))

export default app

4. Run

Run the command.

bun run dev

Then, access http://localhost:3000 in your browser.

Change port number

You can specify the port number with exporting the port.

import { Hono } from 'hono'

const app = new Hono()
app.get('/', (c) => c.text('Hello Bun!'))

export default app 
export default { 
  port: 3000, 
  fetch: app.fetch, 
} 

Serve static files

To server static files, use serveStatic imported from hono/bun.

import { serveStatic } from 'hono/bun'

const app = new Hono()

app.use('/static/*', serveStatic({ root: './' }))
app.use('/favicon.ico', serveStatic({ path: './favicon.ico' }))
app.get('/', (c) => c.text('You can access: /static/hello.txt'))
app.get('*', serveStatic({ path: './static/fallback.txt' }))

For the above code, it will work well with the following directory structure.

./
├── favicon.ico
├── index.ts
└── static
    ├── demo
    │   └── index.html
    ├── fallback.txt
    ├── hello.txt
    └── images
        └── dinotocat.png

rewriteRequestPath

If you want to map http://localhost:3000/static/* to ./statics, you can use the rewriteRequestPath option:

app.get(
  '/static/*',
  serveStatic({
    root: './',
    rewriteRequestPath: (path) => path.replace(/^\/static/, '/statics'),
  })
)

mimes

You can add MIME types with mimes:

app.get(
  '/static/*',
  serveStatic({
    mimes: {
      m3u8: 'application/vnd.apple.mpegurl',
      ts: 'video/mp2t',
    }
  })
)

onNotFound

You can specify handling when the requested file is not found with onNotFound:

app.get(
  '/static/*',
  serveStatic({
    onNotFound: (path, c) => {
      console.log(`${path} is not found, you access ${c.req.path}`)
    },
  })
)

Testing

You can use bun:test for testing on Bun.

import { describe, expect, it } from 'bun:test'
import app from '.'

describe('My first test', () => {
  it('Should return 200 Response', async () => {
    const req = new Request('http://localhost/')
    const res = await app.fetch(req)
    expect(res.status).toBe(200)
  })
})

Then, run the command.

bun test index.test.ts

Obtaining Request IP Address

To obtain the IP address of the client, you need to use Bun.serve. You can use Bindings generics to pass the ip to the context and ensure type safety.

import type { SocketAddress } from 'bun'
import { Hono } from 'hono'

type Bindings = {
  ip: SocketAddress
}

const app = new Hono<{ Bindings: Bindings }>()

app.get('/', (c) => {
  return c.json({
    yourIp: c.env.ip 
    // {yourIp: {"address": "1.1.1", "family": "IPv4", "port": 56071}}
  })
})

Bun.serve({
  fetch(req, server) {
    return app.fetch(req, { ip: server.requestIP(req) })
  }
})