The XMLHttpRequest method getAllResponseHeaders() returns all the response headers, separated by CRLF, as a string, or returns null if no response has been received. If a network error happened, an empty string is returned.

Note: For multipart requests, this returns the headers from the current part of the request, not from the original channel.


var headers = XMLHttpRequest.getAllResponseHeaders();



Return value

A ByteString representing all of the response's headers (except those whose field name is Set-Cookie or Set-Cookie2) separated by CRLF, or null if no response has been received. If a network error happened, an empty string is returned.

An example of what a raw header string looks like:

date: Fri, 08 Dec 2017 21:04:30 GMT\r\n
content-encoding: gzip\r\n
x-content-type-options: nosniff\r\n
server: meinheld/0.6.1\r\n
x-frame-options: DENY\r\n
content-type: text/html; charset=utf-8\r\n
connection: keep-alive\r\n
strict-transport-security: max-age=63072000\r\n
vary: Cookie, Accept-Encoding\r\n
content-length: 6502\r\n
x-xss-protection: 1; mode=block\r\n

Each line is terminated by both carriage return and line feed characters ("\r\n"). These are essentially delimiters separating each of the headers.


This example examines the headers in the request's readystatechange event handler, XMLHttpRequest.onreadystatechange. The code shows how to obtain the raw header string, as well as how to convert it into an array of individual headers and then how to take that array and create a mapping of header names to their values.

var request = new XMLHttpRequest();
request.open("GET", "foo.txt", true);

request.onreadystatechange = function() {
  if(this.readyState == this.HEADERS_RECEIVED) {

    // Get the raw header string
    var headers = request.getAllResponseHeaders();

    // Convert the header string into an array
    // of individual headers
    var arr = headers.trim().split(/[\r\n]+/);

    // Create a map of header names to values
    var headerMap = {};
    arr.forEach(function (line) {
      var parts = line.split(': ');
      var header = parts.shift();
      var value = parts.join(': ');
      headerMap[header] = value;

Once this is done, you can, for example:

var contentType = headerMap["content-type"];

This obtains the value of the Content-Type header into the variable contentType.


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

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support11241



FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes41 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