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  1. Products
  2. Workers
  3. Examples
  4. Alter headers

Alter headers

Example of how to add, change, or delete headers sent in a request or returned in a response.

export default {
  async fetch(request) {
    const response = await fetch(request);


    // Clone the response so that it's no longer immutable
    const newResponse = new Response(response.body, response);


    // Add a custom header with a value
    newResponse.headers.append(
      "x-workers-hello",
      "Hello from Cloudflare Workers"
    );


    // Delete headers
    newResponse.headers.delete("x-header-to-delete");
    newResponse.headers.delete("x-header2-to-delete");


    // Adjust the value for an existing header
    newResponse.headers.set("x-header-to-change", "NewValue");
    return newResponse;
  },

};


const handler: ExportedHandler = {
  async fetch(request: Request) {
    const response = await fetch(request);


    // Clone the response so that it's no longer immutable
    const newResponse = new Response(response.body, response);


    // Add a custom header with a value
    newResponse.headers.append(
      "x-workers-hello",
      "Hello from Cloudflare Workers"
    );


    // Delete headers
    newResponse.headers.delete("x-header-to-delete");
    newResponse.headers.delete("x-header2-to-delete");


    // Adjust the value for an existing header
    newResponse.headers.set("x-header-to-change", "NewValue");
    return newResponse;
  },

};

export default handler;

You can also use the custom-headers-example template to deploy this code to your custom domain.