Headers: keys() method

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

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

Syntax

keys()

Parameters

None.

Return value

Returns an {{jsxref("Iteration_protocols","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

Browser compatibility

{{Compat}}

See also

• ServiceWorker API
• HTTP access control (CORS)
• HTTP