XMLHttpRequest.getResponseHeader()

The XMLHttpRequest.getResponseHeader() method returns the string containing the text of the specified header. 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. The search for the header name is case-insensitive.

Syntax

var myHeader = XMLHttpRequest.getResponseHeader(name);

Parameters

name

A ByteString representing 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

var client = new XMLHttpRequest();
client.open("GET", "unicorns-are-teh-awesome.txt", true);
client.send();
client.onreadystatechange = function() {
  if(this.readyState == this.HEADERS_RECEIVED) {
    console.log(client.getResponseHeader("Content-Type"));
  }
}

Specifications

Browser compatibility

[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] This feature was implemented via ActiveXObject(). Internet Explorer implements the standard XMLHttpRequest since version 7.

See also

• Using XMLHttpRequest