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.

bun create hono my-app

bun create hono my-app

Move into my-app and install the dependencies.

cd my-app
bun install

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

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 --hot src/index.ts

bun run --hot src/index.ts

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

Change port number

You can specify the port number with exporting the port.

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

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' }))

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

./
├── 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'),
  })
)

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

`onNotFound`

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

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

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)
  })
})

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

bun test index.test.ts

Bun ​

1. Install Bun ​

2. Setup ​

3. Hello World ​

4. Run ​

Change port number ​

Serve static files ​

rewriteRequestPath ​

onNotFound ​

Testing ​

Bun