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HTTP Headers

The Headers interface is part of the Fetch API. It allows you create and manipulate the HTTP headers of request and response resources of fetch().

Constructor Jump to heading

The Header() constructor creates a new Header instance.

let headers = new Headers(init);

Parameters Jump to heading

name type optional description
init Headers / { [key: string]: string } true The init option lets you initialize the headers object with an existing Headers or an object literal.

The return type of the constructor is a Headers instance.

Methods Jump to heading

name description
append(name: string, value: string) Appends a header (overwrites existing one) to the Headers object.
delete(name: string) Deletes a header from the Headers object.
set(name: string, value: string) Create a new header in the Headers object.
get(name: string) Get the value of the header in the Headers object.
has(name: string) Check if the header exists in the Headers objects.
entries() Get the headers as key-value pair. The result is iterable.
keys() Get all the keys of the Headers object. The result is iterable.

Example Jump to heading

// Create a new headers object from an object literal.
const myHeaders = new Headers({
  accept: "application/json",

// Append a header to the headers object.
myHeaders.append("user-agent", "Deno Deploy");

// Print the headers of the headers object.
for (const [key, value] of myHeaders.entries()) {
  console.log(key, value);

// You can pass the headers instance to Response or Request constructors.
const request = new Request("https://api.github.com/users/denoland", {
  method: "POST",
  headers: myHeaders,