XMLHttpRequest: getAllResponseHeaders() method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Note: This feature is available in Web Workers, except for Service Workers.
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
getAllResponseHeaders()
Parameters
None.
Return value
A string representing all of the response's headers (except those
whose field name is Set-Cookie) 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.
Examples
This example examines the headers in the request's readystatechange event. 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.
const request = new XMLHttpRequest();
request.open("GET", "foo.txt", true);
request.send();
request.onreadystatechange = () => {
if (request.readyState === request.HEADERS_RECEIVED) {
// Get the raw header string
const headers = request.getAllResponseHeaders();
// Convert the header string into an array
// of individual headers
const arr = headers.trim().split(/[\r\n]+/);
// Create a map of header names to values
const headerMap = {};
arr.forEach((line) => {
const parts = line.split(": ");
const header = parts.shift();
const value = parts.join(": ");
headerMap[header] = value;
});
}
};
Once this is done, you can, for example:
const contentType = headerMap["content-type"];
This obtains the value of the Content-Type header into the variable
contentType.
Specifications
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| XMLHttpRequest # the-getallresponseheaders()-method |
Browser compatibility
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getAllResponseHeaders
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Header names returned in all lower case
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Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- See implementation notes.
See also
- Using XMLHttpRequest
- Setting request headers:
setRequestHeader()