Context #

To handle Request and Response, you can use Context object.

c.req #

// 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')
  ...
})

// Get all params at once
app.get('/entry/:id/comment/:commentId', (c) => {
  const { id, commentId } = c.req.param()
})

// Parse cookie
app.get('/entry/:id', (c) => {
  const value = c.req.cookie('name')
  ...
})

// Parse Request body of type `multipart/form` or `application/x-www-form-urlencoded`
app.post('/entry', async (c) => {
  const body = await c.req.parseBody()
  ...
})

// Parse Request body of type `application/json`
app.post('/entry', async (c) => {
  const body = await c.req.json()
  ...
})

// Parse Request body of type `text/plain`
app.post('/entry', async (c) => {
  const body = await c.req.text()
  ...
})

// Parse Request body as an `ArrayBuffer`
app.post('/entry', async (c) => {
  const body = await c.req.arrayBuffer()
  ...
})

Shortcuts for Response #

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.

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.

app.get('/say', (c) => {
  return c.text('Hello!')
})

c.json() #

Render JSON as Content-Type:application/json.

app.get('/api', (c) => {
  return c.json({ message: 'Hello!' })
})

c.html() #

Render HTML as Content-Type:text/html.

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

c.cookie() #

Set cookie for Response.

app.get('/', (c) => {
  c.cookie('delicious_cookie', 'choco')
  return c.text('Do you like cookie?')
})

c.notFound() #

Return the Not Found Response.

app.get('/notfound', (c) => {
  return c.notFound()
})

c.redirect() #

Redirect, default status code is 302.

app.get('/redirect', (c) => c.redirect('/'))
app.get('/redirect-permanently', (c) => c.redirect('/', 301))

c.res #

// Response object
app.use('/', async (c, next) => {
  await next()
  c.res.headers.append('X-Debug', 'Debug message')
})

c.set/c.get #

Set the value specified by the key with set and use it later with get.

app.use('*', async (c, next) => {
  c.set('message', 'Hono is cool!!')
  await next()
})

app.get('/', (c) => {
  const message = c.get('message')
  return c.text(`The message is "${message}"`)
})

c.executionCtx #

// ExecutionContext object
app.get('/foo', async (c) => {
  c.executionCtx.waitUntil(
    c.env.KV.put(key, data)
  )
  ...
})

c.event #

// 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.

// Environment object for Cloudflare Workers
app.get('*', async c => {
  const counter = c.env.COUNTER
  ...
})

c.error #

If the Handler throw an error, the error object is placed in c.error. You can check it in your middleware.

app.use('*', async (c, next) => {
  await next()
  if (c.error) {
    // do something...
  }
})