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 "create-hono" command.

deno run -A npm:create-hono my-app

Select deno template for this example.

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

cd my-app

3. Hello World

Write your first application.

import { Hono } from 'https://deno.land/x/hono/mod.ts'

const app = new Hono()

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

Deno.serve(app.fetch)

4. Run

Just this command:

deno task start

Change port number

You can specify the port number with the port option.

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

Serve static files

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

import { Hono } from 'https://deno.land/x/hono/mod.ts'
import { serveStatic } from 'https://deno.land/x/hono/middleware.ts'

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',
    }
  })
)

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}`)
    },
  })
)

Deno Deploy

Deno Deploy is an edge runtime platform for Deno. We can publish the application world widely on Deno Deploy.

Hono also supports 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 the standard library.

import { Hono } from 'https://deno.land/x/hono/mod.ts'
import { assertEquals } from 'https://deno.land/std/assert/mod.ts'

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

JSX Pragma

Hono on Deno also supports JSX middleware. When you use it, write JSX Pragma on the top to specify the JSX function.

/** @jsx jsx */
import { Hono } from 'https://deno.land/x/hono/mod.ts'
import { jsx } from 'https://deno.land/x/hono/middleware.ts'

const app = new Hono()

app.get('/', (c) => {
  return c.html(<h1>Hello Deno!</h1>)
})

Deno.serve(app.fetch)

npm: specifier

npm:hono is also available.

import { Hono } from 'npm:hono'

You can use either npm:hono or deno.land/x/hono.

If you want to use Third-party Middleware, you need to use the npm: specifier, such as npm:@hono/zod-validator, and you should avoid using both npm: and deno.land/x/hono together.

However, npm:hono doesn't work on Deno Deploy. So, if you want to deploy to Deno Deploy, use deno.land/x/hono.

As of September 6, 2023, Deno announced native npm support on Deno Deploy. However, it has not been tested yet on the hono and @hono packages.

If you experience any problems, or want to run test, please open an issue/pr to the respective library.