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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().


The Header() constructor creates a new Header instance.

let headers = new Headers(init);


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.


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.


// 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("", {
  method: "POST",
  headers: myHeaders,