Deno

Deno is a JavaScript runtime built on V8. It's not Node.js. Hono also works on Deno.

You can use Hono, write the code with TypeScript, run the application with the deno command, and deploy it to "Deno Deploy".

1. Install Deno

First, install deno command. Please refer to the official document.

2. Setup

A starter for Deno is available. Start your project with the deno init command.

deno init --npm hono my-app --template=deno

Move into my-app. For Deno, you don't have to install Hono explicitly.

cd my-app

3. Hello World

Edit main.ts:

main.ts

import { Hono } from 'hono'

const app = new Hono()

app.get('/', (c) => c.text('Hello Deno!'))

Deno.serve(app.fetch)

4. Run

Run the development server locally. Then, access http://localhost:8000 in your Web browser.

deno task start

Change port number

You can specify the port number by updating the arguments of Deno.serve in main.ts:

Deno.serve(app.fetch) 
Deno.serve({ port: 8787 }, app.fetch) 

Serve static files

To serve static files, use serveStatic imported from hono/deno.

import { Hono } from 'hono'
import { serveStatic } from 'hono/deno'

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' }))

Deno.serve(app.fetch)

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:8000/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',
    },
  })
)

onFound

You can specify handling when the requested file is found with onFound:

app.get(
  '/static/*',
  serveStatic({
    // ...
    onFound: (_path, c) => {
      c.header('Cache-Control', `public, immutable, max-age=31536000`)
    },
  })
)

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}`)
    },
  })
)

precompressed

The precompressed option checks if files with extensions like .br or .gz are available and serves them based on the Accept-Encoding header. It prioritizes Brotli, then Zstd, and Gzip. If none are available, it serves the original file.

app.get(
  '/static/*',
  serveStatic({
    precompressed: true,
  })
)

Deno Deploy

Deno Deploy is a serverless platform for running JavaScript and TypeScript applications in the cloud. It provides a management plane for deploying and running applications through integrations like GitHub deployment.

Hono also works on Deno Deploy. Please refer to the official document.

Testing

Testing the application on Deno is easy. You can write with Deno.test and use assert or assertEquals from @std/assert.

deno add jsr:@std/assert

hello.ts

import { Hono } from 'hono'
import { assertEquals } from '@std/assert'

Deno.test('Hello World', async () => {
  const app = new Hono()
  app.get('/', (c) => c.text('Please test me'))

  const res = await app.request('http://localhost/')
  assertEquals(res.status, 200)
})

Then run the command:

deno test hello.ts

npm and JSR

Hono is available on both npm and JSR (the JavaScript Registry). You can use either npm:hono or jsr:@hono/hono in your deno.json:

{
  "imports": {
    "hono": "jsr:@hono/hono"
    "hono": "npm:hono"
  }
}

When using third-party middleware, you may need to use Hono from the same registry as the middleware for proper TypeScript type inference. For example, if using the middleware from npm, you should also use Hono from npm:

{
  "imports": {
    "hono": "npm:hono",
    "zod": "npm:zod",
    "@hono/zod-validator": "npm:@hono/zod-validator"
  }
}

We also provide many third-party middleware packages on JSR. When using the middleware on JSR, use Hono from JSR:

{
  "imports": {
    "hono": "jsr:@hono/hono",
    "zod": "npm:zod",
    "@hono/zod-validator": "jsr:@hono/zod-validator"
  }
}