Web/API/XMLHTTPRequest/getAllResponseHeaders

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.

Syntax

var headers = XMLHttpRequest.getAllResponseHeaders();

Parameters

None.

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.

Note: In modern browsers, the header names are returned in all lower case, as per the latest spec.

Example

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.send();

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.

Specifications

Specification	Status	Comment
XMLHttpRequestThe definition of 'getAllResponseHeaders()' 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
`getAllResponseHeaders`	Chrome Full support 1	Edge Full support 12	Firefox 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`.	IE Full support 5	Opera Full support Yes	Safari Full support 1.2	WebView Android Full support Yes	Chrome Android Full support Yes	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 Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes
Header names returned in all lower case	Chrome Full support Yes	Edge Full support 79	Firefox Full support 64	IE No support No	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 64	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes

Legend

Full support: Full support
No support: No support
See implementation notes.': See implementation notes.