XMLHttpRequest.getResponseHeader()

The XMLHttpRequest method getResponseHeader() returns the string containing the text of 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

name
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
XMLHttpRequest
The definition of 'getResponseHeader()' in that specification.
Living Standard WHATWG living standard

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support112 Yes1

7

52

Yes1.2
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes1 Yes Yes1 Yes ? Yes

1. 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.

2. Implemented via ActiveXObject

See also

Document Tags and Contributors

Last updated by: Sheppy,