Cloudflare Docs
Visit Workers on GitHub
Set theme to dark (⇧+D)

Modify request property

Create a modified request with edited properties based off of an incoming request.
* Example someHost is set up to return raw JSON
* @param {string} someUrl the URL to send the request to, since we are setting hostname too only path is applied
* @param {string} someHost the host the request will resolve too
const someHost = '';
const someUrl = '';
async function handleRequest(request) {
* The best practice is to only assign new RequestInit properties
* on the request object using either a method or the constructor
const newRequestInit = {
// Change method
method: 'POST',
// Change body
body: JSON.stringify({ bar: 'foo' }),
// Change the redirect mode.
redirect: 'follow',
// Change headers, note this method will erase existing headers
headers: {
'Content-Type': 'application/json',
// Change a Cloudflare feature on the outbound response
cf: { apps: false },
// Change just the host
const url = new URL(someUrl);
url.hostname = someHost;
// Best practice is to always use the original request to construct the new request
// to clone all the attributes. Applying the URL also requires a constructor
// since once a Request has been constructed, its URL is immutable.
const newRequest = new Request(url.toString(), new Request(request, newRequestInit));
// Set headers using method
newRequest.headers.set('X-Example', 'bar');
newRequest.headers.set('Content-Type', 'application/json');
try {
return await fetch(newRequest);
} catch (e) {
return new Response(JSON.stringify({ error: e.message }), { status: 500 });
addEventListener('fetch', event => {