hono-core

name	hono-core
description	Hono ultrafast web framework fundamentals - routing, context, handlers, and response patterns for multi-runtime deployment
user-invocable	false
disable-model-invocation	true
skill_version	1.0.0
updated_at	"2025-01-03T00:00:00.000Z"
tags	["hono","web-framework","routing","typescript","cloudflare-workers","deno","bun","nodejs"]
progressive_disclosure	{"entry_point":{"summary":"Ultrafast web framework built on Web Standards for Cloudflare Workers, Deno, Bun, Node.js","when_to_use":"Building APIs/web apps that need multi-runtime deployment, edge computing, or lightweight performance","quick_start":"1. npm create hono@latest 2. Define routes with app.get/post 3. Return responses via context"},"references":[]}
context_limit	800

Hono - Ultrafast Web Framework

Overview

Hono is a small, simple, and ultrafast web framework built on Web Standards. It runs on Cloudflare Workers, Deno, Bun, Node.js, and more with the same codebase. The name means "flame" in Japanese.

Key Features:

• Built on Web Standards (Request/Response/fetch)
• Multi-runtime: Cloudflare Workers, Deno, Bun, Node.js, Vercel, AWS Lambda
• Ultrafast routing with RegExpRouter
• First-class TypeScript support
• Lightweight (~14KB minified)
• Rich middleware ecosystem

Installation:

# Create new project (recommended)
npm create hono@latest my-app

# Or install in existing project
npm install hono

# Runtime-specific adapters
npm install @hono/node-server  # Node.js

When to Use This Skill

Use Hono when:

• Building APIs for edge/serverless environments (Cloudflare Workers, Vercel Edge)
• Need multi-runtime portability (same code on Bun, Deno, Node.js)
• Want TypeScript-first development with excellent type inference
• Building lightweight, high-performance APIs
• Need built-in middleware for common patterns (CORS, auth, compression)

Hono vs Other Frameworks:

• Hono: Multi-runtime, Web Standards, ultrafast, edge-optimized
• Express: Node.js only, larger ecosystem, slower
• Fastify: Node.js only, schema-based, good performance
• Elysia: Bun only, excellent performance, different API style

Core Concepts

Creating an Application

import { Hono } from 'hono'

const app = new Hono()

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

export default app

With TypeScript Generics (for bindings/variables):

type Bindings = {
  DATABASE_URL: string
  API_KEY: string
}

type Variables = {
  user: { id: string; name: string }
}

const app = new Hono<{ Bindings: Bindings; Variables: Variables }>()

The Context Object (c)

The context c provides access to request data and response methods:

app.get('/users/:id', async (c) => {
  // Request data
  const id = c.req.param('id')           // Path parameter
  const query = c.req.query('sort')       // Query parameter ?sort=asc
  const queries = c.req.queries('tags')   // Multiple: ?tags=a&tags=b
  const header = c.req.header('Authorization')
  const body = await c.req.json()         // JSON body
  const form = await c.req.formData()     // Form data

  // Environment (Cloudflare Workers bindings)
  const db = c.env.DATABASE_URL

  // Custom variables (set by middleware)
  const user = c.get('user')

  // Response methods
  return c.text('Plain text')
  return c.json({ id, name: 'User' })
  return c.html('<h1>Hello</h1>')
  return c.redirect('/login')
  return c.notFound()
})

Response Methods

// Text response
c.text('Hello', 200)

// JSON response
c.json({ message: 'Success' }, 201)
c.json({ error: 'Not found' }, 404)

// HTML response
c.html('<h1>Hello</h1>')

// Redirect
c.redirect('/login')           // 302 default
c.redirect('/login', 301)      // Permanent redirect

// Headers
c.header('X-Custom', 'value')
c.header('Cache-Control', 'max-age=3600')

// Streaming
c.streamText(async (stream) => {
  await stream.write('Hello ')
  await stream.write('World!')
})

// Raw Response
return new Response('Raw', { status: 200 })

Routing Patterns

Basic Routing

const app = new Hono()

// HTTP methods
app.get('/users', getUsers)
app.post('/users', createUser)
app.put('/users/:id', updateUser)
app.delete('/users/:id', deleteUser)
app.patch('/users/:id', patchUser)

// All methods
app.all('/webhook', handleWebhook)

// Custom methods
app.on('PURGE', '/cache', purgeCache)
app.on(['GET', 'POST'], '/form', handleForm)

Path Parameters

// Single parameter
app.get('/users/:id', (c) => {
  const id = c.req.param('id')
  return c.json({ id })
})

// Multiple parameters
app.get('/posts/:postId/comments/:commentId', (c) => {
  const { postId, commentId } = c.req.param()
  return c.json({ postId, commentId })
})

// Optional parameter
app.get('/api/animal/:type?', (c) => {
  const type = c.req.param('type') || 'all'
  return c.json({ type })
})

// Regex validation
app.get('/posts/:id{[0-9]+}', (c) => {
  const id = c.req.param('id')  // Only numeric IDs
  return c.json({ id })
})

// Wildcards
app.get('/files/*', (c) => {
  const path = c.req.param('*')  // Everything after /files/
  return c.text(`File: ${path}`)
})

Route Grouping

// Using app.route()
const api = new Hono()
api.get('/users', getUsers)
api.get('/posts', getPosts)

const app = new Hono()
app.route('/api/v1', api)  // /api/v1/users, /api/v1/posts

// Using basePath()
const v2 = new Hono().basePath('/api/v2')
v2.get('/users', getUsers)  // /api/v2/users

// Chaining
app
  .get('/a', handlerA)
  .post('/b', handlerB)
  .delete('/c', handlerC)

Route Organization (Multi-File)

// routes/users.ts
import { Hono } from 'hono'

const users = new Hono()

users.get('/', async (c) => {
  return c.json({ users: [] })
})

users.post('/', async (c) => {
  const body = await c.req.json()
  return c.json({ created: body }, 201)
})

users.get('/:id', async (c) => {
  const id = c.req.param('id')
  return c.json({ id })
})

export default users

// app.ts
import { Hono } from 'hono'
import users from './routes/users'
import posts from './routes/posts'

const app = new Hono()

app.route('/users', users)
app.route('/posts', posts)

export default app

Handler Patterns

Inline Handlers

// Simple handler
app.get('/hello', (c) => c.text('Hello!'))

// Async handler
app.get('/users', async (c) => {
  const users = await fetchUsers()
  return c.json({ users })
})

// Multiple handlers (middleware chain)
app.get('/admin', authenticate, authorize, (c) => {
  return c.json({ admin: true })
})

Using Factory for Type-Safe Handlers

import { createFactory } from 'hono/factory'

const factory = createFactory<{ Bindings: Bindings }>()

// Create typed handler
const getUser = factory.createHandlers(async (c) => {
  const id = c.req.param('id')
  const db = c.env.DATABASE_URL  // Typed!
  return c.json({ id })
})

app.get('/users/:id', ...getUser)

Error Handling

Built-in Error Handling

import { HTTPException } from 'hono/http-exception'

app.get('/users/:id', async (c) => {
  const user = await findUser(c.req.param('id'))

  if (!user) {
    throw new HTTPException(404, { message: 'User not found' })
  }

  return c.json(user)
})

// Global error handler
app.onError((err, c) => {
  console.error(`${err}`)

  if (err instanceof HTTPException) {
    return err.getResponse()
  }

  return c.json({ error: 'Internal Server Error' }, 500)
})

// Not found handler
app.notFound((c) => {
  return c.json({ error: 'Route not found' }, 404)
})

Custom Error Classes

class ValidationError extends HTTPException {
  constructor(errors: string[]) {
    super(400, {
      message: 'Validation failed',
      cause: errors
    })
  }
}

class AuthenticationError extends HTTPException {
  constructor() {
    super(401, { message: 'Authentication required' })
  }
}

Runtime-Specific Exports

Cloudflare Workers

// src/index.ts
import { Hono } from 'hono'

const app = new Hono()
app.get('/', (c) => c.text('Hello Cloudflare!'))

export default app

Node.js

// src/index.ts
import { serve } from '@hono/node-server'
import { Hono } from 'hono'

const app = new Hono()
app.get('/', (c) => c.text('Hello Node!'))

serve({
  fetch: app.fetch,
  port: 3000
})

Bun

// src/index.ts
import { Hono } from 'hono'

const app = new Hono()
app.get('/', (c) => c.text('Hello Bun!'))

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

Deno

// main.ts
import { Hono } from 'npm:hono'

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

Deno.serve(app.fetch)

Best Practices

Write Handlers Inline (Not Controllers)

// CORRECT: Inline handlers with proper type inference
app.get('/users/:id', async (c) => {
  const id = c.req.param('id')  // Type: string
  return c.json({ id })
})

// AVOID: Controller-style (loses type inference)
class UserController {
  getUser(c: Context) {
    const id = c.req.param('id')  // Type: string | undefined
    return c.json({ id })
  }
}

Use Modular Routes

// CORRECT: Split routes by domain
// routes/users.ts
export const users = new Hono()
  .get('/', listUsers)
  .post('/', createUser)
  .get('/:id', getUser)

// app.ts
app.route('/users', users)

Type Everything

// Define your environment bindings
type Bindings = {
  DATABASE_URL: string
  JWT_SECRET: string
  MY_KV: KVNamespace
}

// Pass to Hono
const app = new Hono<{ Bindings: Bindings }>()

// Now c.env is fully typed
app.get('/', (c) => {
  const url = c.env.DATABASE_URL  // string
  const kv = c.env.MY_KV          // KVNamespace
})

Quick Reference

Common Context Methods

Method	Description	Example
c.req.param(name)	Get path parameter	c.req.param('id')
c.req.query(name)	Get query parameter	c.req.query('page')
c.req.header(name)	Get request header	c.req.header('Authorization')
c.req.json()	Parse JSON body	await c.req.json()
c.req.formData()	Parse form data	await c.req.formData()
c.text(str, status)	Text response	c.text('OK', 200)
c.json(obj, status)	JSON response	c.json({}, 201)
c.html(str)	HTML response	c.html('<h1>Hi</h1>')
c.redirect(url)	Redirect	c.redirect('/login')
c.header(k, v)	Set response header	c.header('X-Custom', 'val')
c.set(key, val)	Set context variable	c.set('user', user)
c.get(key)	Get context variable	c.get('user')
c.env	Environment bindings	c.env.API_KEY

HTTP Methods

app.get(path, ...handlers)
app.post(path, ...handlers)
app.put(path, ...handlers)
app.delete(path, ...handlers)
app.patch(path, ...handlers)
app.options(path, ...handlers)
app.head(path, ...handlers)
app.all(path, ...handlers)
app.on(method, path, ...handlers)

Related Skills

• hono-middleware - Middleware patterns and composition
• hono-validation - Request validation with Zod
• hono-rpc - Type-safe RPC client
• hono-testing - Testing patterns
• hono-jsx - Server-side JSX rendering
• hono-cloudflare - Cloudflare Workers deployment

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Version: Hono 4.x Last Updated: January 2025 License: MIT