H3 is a minimal h(ttp) framework built for high performance and portability

Features

✔️ Portable: Works perfectly in Serverless, Workers, and Node.js

✔️ Compatible: Support connect/express middleware

✔️ Minimal: Small, tree-shakable and zero-dependency

✔️ Modern: Native promise support

✔️Extendable: Ships with a set of composable utilities but can be extended

# Using npm
npm install h3

# Using yarn
yarn add h3

import { createServer } from 'http'
import { createApp } from 'h3'

const app = createApp()
app.use('/', () => 'Hello world!')

createServer(app).listen(process.env.PORT || 3000)

Tip: you may try listhen for a more elegant and advanced listener.

// Handle can directly return object or Promise<object> for JSON response
app.use('/api', (req) => ({ url: req.url }))

// We can have better matching other than quick prefix match
app.use('/odd', () => 'Is odd!', { match: url => url.substr(1) % 2 })

// Handle can directly return string for HTML response
app.use(() => '<h1>Hello world!</h1>')

// We can chain calls to .use()
app.use('/1', () => '<h1>Hello world!</h1>')
   .use('/2', () => '<h1>Goodbye!</h1>')

// Legacy middleware with 3rd argument are automatically promisified
app.use((req, res, next) => { req.setHeader('X-Foo', 'bar'); next() })

// Force promisify a legacy middleware
// app.use(someMiddleware, { promisify: true })

// Lazy loaded routes using { lazy: true }
// app.use('/big', () => import('./big'), { lazy: true })

Instead of adding helpers to req and res, h3 exposes them as composable utilities.

• useRawBody(req, encoding?)
• useBody(req)
• useCookies(req)
• useCookie(req, name)
• setCookie(req, name, value, opts?)
• useQuery(req)
• send(res, data, type?)
• sendRedirect(res, location, code=302)
• appendHeader(res, name, value)
• createError({ statusCode, statusMessage, data? }
• sendError(res, error, debug?)

Using createApp, it returns a standard (req, res) handler function and internally an array called middleware stack. usinguse() method we can to add an item to this internal stack.

When a request comes, each stack item that matches the route will be called and resolved until res.writableEnded flag is set, which means the response is sent. If writableEnded is not set after all middleware, a 404 error will be thrown. And if one of the stack items resolves to a value, it will be serialized and sent as response as a shorthand method to sending responses.

For maximum compatibility with connect/express middleware (req, res, next? signature), h3 converts classic middleware into a promisified version ready to use with stack runner:

• If middleware has 3rd next/callback param, promise will resolve/reject when called
• If middleware returns a promise, it will be chained to the main promise
• If calling middleware throws an immediate error, promise will be rejected
• On close and error events of res, promise will resolve/reject (to ensure if middleware simply calls res.end)

MIT