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 |
---|---|---|
XMLHttpRequest The definition of 'getAllResponseHeaders()' in that specification. |
Living Standard | WHATWG living standard |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
getAllResponseHeaders | Chrome Full support 1 | Edge Full support 12 | Firefox
Full support
4
| 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
| 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.
See also
- Using XMLHttpRequest
- Setting request headers:
setRequestHeader()