Headers: keys() method

~~{{APIRef("Fetch API")}} {{AvailableInWorkers}}~~

The Headers.keys() method returns an ~~{{jsxref("Iteration_protocols",'iterator')}}~~iterator allowing you to go through all keys contained in this object. The keys are ~~{{jsxref("String")}}~~String objects.

Syntax

keys()

Parameters

None.

Return value

Returns an ~~{{jsxref("Iteration_protocols","iterator")}}~~iterator.

Examples

// Create a test Headers object
const myHeaders = new Headers();
myHeaders.append("Content-Type", "text/xml");
myHeaders.append("Vary", "Accept-Language");

// Display the keys
for (const key of myHeaders.keys()) {
  console.log(key);
}

The result is:

content-type
vary

Specifications

~~{{Specifications}}~~

Browser compatibility

~~{{Compat}}~~