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Hono - _**[炎] means flame🔥 in Japanese**_ - is a small, simple, and ultrafast web framework for Cloudflare Workers or Service Worker based serverless such as Fastly Compute@Edge.
```ts
import { Hono } from 'hono'
const app = new Hono()
app.get('/', (c) => c.text('Hono!!'))
app.fire()
```
## Features
- **Ultrafast** - the router does not use linear loops.
- **Zero-dependencies** - using only Service Worker and Web Standard API.
- **Middleware** - built-in middleware and ability to extend with your own middleware.
- **TypeScript** - first-class TypeScript support.
- **Optimized** - for Cloudflare Workers.
## Benchmark
**Hono is fastest**, compared to other routers for Cloudflare Workers.
```plain
hono - trie-router(default) x 389,510 ops/sec ±3.16% (85 runs sampled)
hono - regexp-router x 452,290 ops/sec ±2.64% (84 runs sampled)
itty-router x 206,013 ops/sec ±3.39% (90 runs sampled)
sunder x 323,131 ops/sec ±0.75% (97 runs sampled)
worktop x 191,218 ops/sec ±2.70% (91 runs sampled)
Fastest is hono - regexp-router
✨ Done in 43.56s.
```
## Why so fast?
Routers used in Hono are really smart.
- **TrieRouter**(default) - Implemented with Trie tree structure.
- **RegExpRouter** - Match the route with using one big Regex made before dispatch.
## Hono in 1 minute
A demonstration to create an application for Cloudflare Workers with Hono.
## Not only fast
Hono is fast. But not only fast.
### Write Less, do more
Built-in middleware make _"**Write Less, do more**"_ in reality. You can use a lot of middleware without writing code from scratch. Below are examples.
- [Basic Authentication](https://github.com/honojs/hono/tree/master/src/middleware/basic-auth/)
- [Cookie parsing / serializing](https://github.com/honojs/hono/tree/master/src/middleware/cookie/)
- [CORS](https://github.com/honojs/hono/tree/master/src/middleware/cors/)
- [ETag](https://github.com/honojs/hono/tree/master/src/middleware/etag/)
- [GraphQL Server](https://github.com/honojs/hono/tree/master/src/middleware/graphql-server/)
- [html](https://github.com/honojs/hono/tree/master/src/middleware/html/)
- [JSX](https://github.com/honojs/hono/tree/master/src/middleware/jsx/)
- [JWT Authentication](https://github.com/honojs/hono/tree/master/src/middleware/jwt/)
- [Logger](https://github.com/honojs/hono/tree/master/src/middleware/logger/)
- [Mustache template engine](https://github.com/honojs/hono/tree/master/src/middleware/mustache/) (Only for Cloudflare Workers)
- [JSON pretty printing](https://github.com/honojs/hono/tree/master/src/middleware/pretty-json/)
- [Serving static files](https://github.com/honojs/hono/tree/master/src/middleware/serve-static/) (Only for Cloudflare Workers)
To enable logger and Etag middleware with just this code.
```ts
import { Hono } from 'hono'
import { etag } from 'hono/etag'
import { logger } from 'hono/logger'
const app = new Hono()
app.use('*', etag(), logger())
```
And, the routing of Hono is so flexible. It's easy to construct large web applications.
```ts
import { Hono } from 'hono'
import { basicAuth } from 'hono/basic-auth'
const v1 = new Hono()
v1.get('/posts', (c) => {
return c.text('list posts')
})
.post(basicAuth({ username, password }), (c) => {
return c.text('created!', 201)
})
.get('/posts/:id', (c) => {
const id = c.req.param('id')
return c.text(`your id is ${id}`)
})
const app = new Hono()
app.route('/v1', v1)
```
### Web Standard
Request and Response object used in Hono are extensions of the Web Standard [Fetch API](https://developer.mozilla.org/ja/docs/Web/API/Fetch_API). If you are familiar with that, you don't need to know more than that.
### Developer Experience
Hono provides fine _"**Developer Experience**"_. Easy access to Request/Response thanks to the `Context` object.
Above all, Hono is written in TypeScript. So, Hono has _"**Types**"_!
For example, the named path parameters will be literal types.
## Install
You can install Hono from the npm registry.
```sh
npm install hono
```
## 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)
## Routing
### Basic
```ts
// HTTP Methods
app.get('/', (c) => c.text('GET /'))
app.post('/', (c) => c.text('POST /'))
app.put('/', (c) => c.text('PUT /'))
app.delete('/', (c) => c.text('DELETE /'))
// Wildcard
app.get('/wild/*/card', (c) => {
return c.text('GET /wild/*/card')
})
// Any HTTP methods
app.all('/hello', (c) => c.text('Any Method /hello'))
```
### Named Parameter
```ts
app.get('/user/:name', (c) => {
const name = c.req.param('name')
...
})
```
or all parameters at once:
```ts
app.get('/posts/:id/comment/:comment_id', (c) => {
const { id, comment_id } = c.req.param()
...
})
```
### Regexp
```ts
app.get('/post/:date{[0-9]+}/:title{[a-z]+}', (c) => {
const { date, title } = c.req.param()
...
})
```
### Chained route
```ts
app
.get('/endpoint', (c) => {
return c.text('GET /endpoint')
})
.post((c) => {
return c.text('POST /endpoint')
})
.delete((c) => {
return c.text('DELETE /endpoint')
})
```
### no strict
If `strict` is set false, `/hello`and`/hello/` are treated the same.
```ts
const app = new Hono({ strict: false }) // Default is true
app.get('/hello', (c) => c.text('/hello or /hello/'))
```
### async/await
```js
app.get('/fetch-url', async (c) => {
const response = await fetch('https://example.com/')
return c.text(`Status is ${response.status}`)
})
```
## Grouping
Group the routes with `Hono` instance and add them to the main app with `route` method.
```ts
const book = new Hono()
book.get('/', (c) => c.text('List Books')) // GET /book
book.get('/:id', (c) => {
// GET /book/:id
const id = c.req.param('id')
return c.text('Get Book: ' + id)
})
book.post('/', (c) => c.text('Create Book')) // POST /book
const app = new Hono()
app.route('/book', book)
```
## Middleware
Middleware works after/before Handler. We can get `Request` before dispatching or manipulate `Response` after dispatching.
### Definition of Middleware
- Handler - should return `Response` object. Only one handler will be called.
- Middleware - should return nothing, will be proceeded to next middleware with `await next()`
The user can register middleware using `c.use` or using `c.HTTP_METHOD` as well as the handlers. For this feature, it's easy to specify the path and the method.
```ts
// match any method, all routes
app.use('*', logger())
// specify path
app.use('/posts/*', cors())
// specify method and path
app.post('/posts/*', basicAuth(), bodyParse())
```
If the handler returns `Response`, it will be used for the end-user, and stopping the processing.
```ts
app.post('/posts', (c) => c.text('Created!', 201))
```
In this case, four middleware are processed before dispatching like this:
```ts
logger() -> cors() -> basicAuth() -> bodyParse() -> *handler*
```
### Built-in Middleware
Hono has built-in middleware.
```ts
import { Hono } from 'hono'
import { poweredBy } from 'hono/powered-by'
import { logger } from 'hono/logger'
import { basicAuth } from 'hono/basicAuth'
const app = new Hono()
app.use('*', poweredBy())
app.use('*', logger())
app.use(
'/auth/*',
basicAuth({
username: 'hono',
password: 'acoolproject',
})
)
```
Available built-in middleware is listed on [src/middleware](https://github.com/honojs/hono/tree/master/src/middleware).
### Custom Middleware
You can write your own middleware.
```ts
// Custom logger
app.use('*', async (c, next) => {
console.log(`[${c.req.method}] ${c.req.url}`)
await next()
})
// Add a custom header
app.use('/message/*', async (c, next) => {
await next()
c.header('x-message', 'This is middleware!')
})
app.get('/message/hello', (c) => c.text('Hello Middleware!'))
```
## Not Found
`app.notFound` for customizing Not Found Response.
```js
app.notFound((c) => {
return c.text('Custom 404 Message', 404)
})
```
## Error Handling
`app.onError` handle the error and return the customized Response.
```js
app.onError((err, c) => {
console.error(`${err}`)
return c.text('Custom Error Message', 500)
})
```
## Context
To handle Request and Response, you can use `Context` object.
### c.req
```ts
// Get Request object
app.get('/hello', (c) => {
const userAgent = c.req.headers.get('User-Agent')
...
})
// Shortcut to get a header value
app.get('/shortcut', (c) => {
const userAgent = c.req.header('User-Agent')
...
})
// Query params
app.get('/search', (c) => {
const query = c.req.query('q')
...
})
// Get all params at once
app.get('/search', (c) => {
const { q, limit, offset } = c.req.query()
...
})
// Multiple query values
app.get('/search', (c) => {
const queries = c.req.queries('q')
// ---> GET search?q=foo&q=bar
// queries[0] => foo, queries[1] => bar
...
})
// Captured params
app.get('/entry/:id', (c) => {
const id = c.req.param('id')
...
})
```
### Shortcuts for Response
```ts
app.get('/welcome', (c) => {
// Set headers
c.header('X-Message', 'Hello!')
c.header('Content-Type', 'text/plain')
// Set HTTP status code
c.status(201)
// Return the response body
return c.body('Thank you for comming')
})
```
The Response is the same as below.
```ts
new Response('Thank you for comming', {
status: 201,
headers: {
'X-Message': 'Hello',
'Content-Type': 'text/plain',
},
})
```
### c.text()
Render text as `Content-Type:text/plain`.
```ts
app.get('/say', (c) => {
return c.text('Hello!')
})
```
### c.json()
Render JSON as `Content-Type:application/json`.
```ts
app.get('/api', (c) => {
return c.json({ message: 'Hello!' })
})
```
### c.html()
Render HTML as `Content-Type:text/html`.
```ts
app.get('/', (c) => {
return c.html('Hello! Hono!
')
})
```
### c.notFound()
Return the `Not Found` Response.
```ts
app.get('/notfound', (c) => {
return c.notFound()
})
```
### c.redirect()
Redirect, default status code is `302`.
```ts
app.get('/redirect', (c) => c.redirect('/'))
app.get('/redirect-permanently', (c) => c.redirect('/', 301))
```
### c.res
```ts
// Response object
app.use('/', async (c, next) => {
await next()
c.res.headers.append('X-Debug', 'Debug message')
})
```
### c.executionCtx
```ts
// ExecutionContext object
app.get('/foo', async (c) => {
c.executionCtx.waitUntil(
c.env.KV.put(key, data)
)
...
})
```
### c.event
```ts
// FetchEvent object (only set when using Service Worker syntax)
app.get('/foo', async (c) => {
c.event.waitUntil(
c.env.KV.put(key, data)
)
...
})
```
### c.env
Environment variables, secrets, and KV namespaces are known as bindings. Regardless of type, bindings are always available as global variables and can be accessed via the context `c.env.BINDING_KEY`.
```ts
// Environment object for Cloudflare Workers
app.get('*', async c => {
const counter = c.env.COUNTER
...
})
```
## fire
`app.fire()` do this.
```ts
addEventListener('fetch', (event) => {
event.respondWith(this.handleEvent(event))
})
```
## fetch
`app.fetch` for Cloudflare Module Worker syntax.
```ts
export default {
fetch(request: Request, env: Env, ctx: ExecutionContext) {
return app.fetch(request, env, ctx)
},
}
```
or just do:
```ts
export default app
```
## request
`request` is a useful method for testing.
```js
test('GET /hello is ok', async () => {
const res = await app.request('http://localhost/hello')
expect(res.status).toBe(200)
})
```
## router
The `router` option specify which router is used inside. The default router is `TrieRouter`. If you want to use `RexExpRouter`, write like this:
```ts
import { RegExpRouter } from 'hono/router/reg-exp-router'
const app = new Hono({ router: new RegExpRouter() })
```
## Routing priority
Handlers or middleware will be executed in registration order.
```ts
app.get('/book/a', (c) => c.text('a')) // a
app.get('/book/:slug', (c) => c.text('common')) // common
```
```http
GET /book/a ---> `a`
GET /book/b ---> `common`
```
When a handler is executed, the process will be stopped.
```ts
app.get('*', (c) => c.text('common')) // common
app.get('/foo', (c) => c.text('foo')) // foo
```
```http
GET /foo ---> `common` // foo will not be dispatched
```
If you have the middleware that you want to execute, write the code above the handler.
```ts
app.use('*', logger())
app.get('/foo', (c) => c.text('foo'))
```
If you want a "_fallback_" handler, write the code below the other handler.
```ts
app.get('/foo', (c) => c.text('foo')) // foo
app.get('*', (c) => c.text('fallback')) // fallback
```
```http
GET /bar ---> `fallback`
```
## Cloudflare Workers with Hono
Using [Wrangler](https://developers.cloudflare.com/workers/cli-wrangler/), you can develop the application locally and publish it with few commands.
Let's write your first code for Cloudflare Workers with Hono.
### 1. `wrangler init`
Initialize as a wrangler project.
```
mkdir hono-example
cd hono-example
npx wrangler init -y
```
### 2. `npm install hono`
Install `hono` from the npm registry.
```
npm init -y
npm i hono
```
### 3. Write your app
Edit `src/index.ts`. Only 4 lines!!
```ts
// src/index.ts
import { Hono } from 'hono'
const app = new Hono()
app.get('/', (c) => c.text('Hello! Hono!'))
app.fire()
```
### 4. Run
Run the development server locally. Then, access `http://127.0.0.1:8787/` in your Web browser.
```
npx wrangler dev
```
### 5. Publish
Deploy to Cloudflare. That's all!
```
npx wrangler publish ./src/index.ts
```
## Starter template
You can start making your Cloudflare Workers application with [the starter template](https://github.com/honojs/hono-minimal). It is really minimal using TypeScript, esbuild, Miniflare, and Jest.
To generate a project skeleton, run this command.
```
npx create-cloudflare my-app https://github.com/honojs/hono-minimal
```
## Practical Example
How about writing web API with Hono?
```ts
import { Hono } from 'hono'
import { cors } from 'hono/cors'
import { basicAuth } from 'hono/basic-auth'
import { prettyJSON } from 'hono/pretty-json'
import { getPosts, getPost, createPost, Post } from './model'
const app = new Hono()
app.get('/', (c) => c.text('Pretty Blog API'))
app.use('*', prettyJSON())
app.notFound((c) => c.json({ message: 'Not Found', ok: false }, 404))
export interface Bindings {
USERNAME: string
PASSWORD: string
}
const api = new Hono()
api.use('/posts/*', cors())
api.get('/posts', (c) => {
const { limit, offset } = c.req.query()
const posts = getPosts({ limit, offset })
return c.json({ posts })
})
api.get('/posts/:id', (c) => {
const id = c.req.param('id')
const post = getPost({ id })
return c.json({ post })
})
api.post(
'/posts',
async (c, next) => {
const auth = basicAuth({ username: c.env.USERNAME, password: c.env.PASSWORD })
await auth(c, next)
},
async (c) => {
const post = await c.req.json()
const ok = createPost({ post })
return c.json({ ok })
}
)
app.route('/api', api)
export default app
```
## Other Examples
- Hono Examples -
## Related projects
Implementation of the original router `TrieRouter` is inspired by [goblin](https://github.com/bmf-san/goblin). `RegExpRouter` is inspired by [Router::Boom](https://github.com/tokuhirom/Router-Boom). API design is inspired by [express](https://github.com/expressjs/express) and [koa](https://github.com/koajs/koa). [itty-router](https://github.com/kwhitley/itty-router), [Sunder](https://github.com/SunderJS/sunder), and [worktop](https://github.com/lukeed/worktop) are the other routers or frameworks for Cloudflare Workers.
- express -
- koa -
- itty-router -
- Sunder -
- goblin -
- worktop -
- Router::Boom -
## Contributing
Contributions Welcome! You can contribute in the following ways.
- Write or fix documents
- Write code of middleware
- Fix bugs
- Refactor the code
- etc.
## Contributors
Thanks to [all contributors](https://github.com/honojs/hono/graphs/contributors)! Especially, [@metrue](https://github.com/metrue) and [@usualoma](https://github.com/usualoma)!
## Author
Yusuke Wada
## License
Distributed under the MIT License. See [LICENSE](LICENSE) for more information.
