Hono(API) #

Hono is primary object. It will be imported first and used until the end.

import { Hono } from 'hono'

const app = new Hono()
//...

export default app // for Cloudflare Workers

Methods #

An instance of Hono has these methods.

• app.HTTP_METHOD([path,]handler|middleware…)
• app.all([path,]handler|middleware…)
• app.route(path, [app])
• app.use([path,]middleware)
• app.notFound(handler)
• app.onError(err, handler)
• app.fire()
• app.fetch(request, env, event)
• app.request(path, options)

The first part of them is used for routing, please refer to the routing section.

Not Found #

app.notFound for customizing Not Found Response.

app.notFound((c) => {
  return c.text('Custom 404 Message', 404)
})

Error Handling #

app.onError handle the error and return the customized Response.

app.onError((err, c) => {
  console.error(`${err}`)
  return c.text('Custom Error Message', 500)
})

fire #

app.fire() do this.

addEventListener('fetch', (event) => {
  event.respondWith(this.handleEvent(event))
})

fetch #

app.fetch will be entry point of your application.

For Cloudflare Workers, you can write below:

export default {
  fetch(request: Request, env: Env, ctx: ExecutionContext) {
    return app.fetch(request, env, ctx)
  },
}

or just do:

export default app

Deno:

serve(app.fetch)

Bun:

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

request #

request is a useful method for testing.

test('GET /hello is ok', async () => {
  const res = await app.request('http://localhost/hello')
  expect(res.status).toBe(200)
})

router option #

The router option specify which router is used inside. The default router is TrieRouter. If you want to use RegExpRouter, write like this:

import { RegExpRouter } from 'hono/router/reg-exp-router'

const app = new Hono({ router: new RegExpRouter() })