Example of a worker adding a header value and returning a response in a specific condition

cloudflareWorkerExample.js

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

/**
 * Fetch and log a request
 * @param {Request} request
 */
async function handleRequest(request) {
  var currentDateTime = new Date()
  console.log(currentDateTime.getHours())
  if (currentDateTime.getHours() > 20) {
    console.log('Disabling access as its late')
    return new Response('Not found', { status: 404 })
  }

  console.log('Got request', request)
  const response = await fetch(request)

  console.log('response received - adding the ben-version to the header')
  const newHeaders = new Headers(response.headers)
  newHeaders.append('ben-version', '2018-10-10')
    
  return new Response(response.body, {
    status: response.status,
    statusText: response.statusText,
    headers: newHeaders
  })
}