Cloudflare worker HTTP basic auth

index.js

addEventListener('fetch', e => {
  e.respondWith(handleReq(e.request))
})

const handleReq = async (req) => {
  if (!req.headers.has('Authorization')) {
    return new Response(null, {
      status: 401,
      headers: {'WWW-Authenticate': 'Basic realm="mylmoe admin secret"'}
    })
  }

  const auth = req.headers.get('Authorization')
  if (auth.substring(0, 6) !== 'Basic ') {
    return new Response(null, {status: 403})
  }

  let secret = null
  try {
    secret = atob(auth.substring(6))
  } catch (e) {
    return new Response(null, {status: 403})
  }

  if (secret !== SECRET) {
    return new Response(null, {status: 403})
  }

  const body = await req.json()

  return new Response(JSON.stringify(body), {status: 200})
}