Web/API/XMLHTTPRequest/getResponseHeader

The XMLHttpRequest method getResponseHeader() returns the string containing the text of a particular header's value. If there are multiple response headers with the same name, then their values are returned as a single concatenated string, where each value is separated from the previous one by a pair of comma and space. The getResponseHeader() method returns the value as a UTF byte sequence.

Note: The search for the header name is case-insensitive.

If you need to get the raw string of all of the headers, use the getAllResponseHeaders() method, which returns the entire raw header string.

Syntax

var myHeader = XMLHttpRequest.getResponseHeader(headerName);

Parameters

headerName: A ByteString indicating the name of the header you want to return the text value of.

Return value

A ByteString representing the header's text value, or null if either the response has not yet been received or the header doesn't exist in the response.

Example

In this example, a request is created and sent, and a readystatechange handler is established to look for the readyState to indicate that the headers have been received; when that is the case, the value of the Content-Type header is fetched. If the Content-Type isn't the desired value, the XMLHttpRequest is canceled by calling abort().

var client = new XMLHttpRequest();
client.open("GET", "unicorns-are-teh-awesome.txt", true);
client.send();

client.onreadystatechange = function() {
  if(this.readyState == this.HEADERS_RECEIVED) {
    var contentType = client.getResponseHeader("Content-Type");
    if (contentType != my_expected_type) {
      client.abort();
    }
  }
}

Specifications

Specification	Status	Comment
XMLHttpRequestThe definition of 'getResponseHeader()' in that specification.	Living Standard	WHATWG living standard

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`getResponseHeader`	Chrome Full support 1	Edge Full support 12	Firefox Full support 1 Notes' Full support 1 Notes' Notes' Starting from Firefox 49, empty headers are returned as empty strings in case the preference `network.http.keep_empty_response_headers_as_empty_string` is set to `true`, defaulting to `false`. Before Firefox 49 empty headers had been ignored. Since Firefox 50 the preference defaults to `true`.	IE Full support 5	Opera Full support 8	Safari Full support 1.2	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4 Notes' Full support 4 Notes' Notes' Starting from Firefox 49, empty headers are returned as empty strings in case the preference `network.http.keep_empty_response_headers_as_empty_string` is set to `true`, defaulting to `false`. Before Firefox 49 empty headers had been ignored. Since Firefox 50 the preference defaults to `true`.	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0

Legend

Full support: Full support
See implementation notes.': See implementation notes.