Cloudflare Docs
Workers
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.

export default {
async fetch(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 = "example.com";
const someUrl = "https://foo.example.com/api.js";
/**
* 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,
});
}
},
};

const handler: ExportedHandler = {
async fetch(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 = "example.com";
const someUrl = "https://foo.example.com/api.js";
/**
* 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,
});
}
},
};
export default handler;