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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

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
getAllResponseHeadersChrome Full support 1Edge Full support 12Firefox 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 7
Full support 7
Full support 5
Notes
Notes Implemented via ActiveXObject
Opera Full support YesSafari Full support 1.2WebView Android Full support YesChrome Android Full support YesEdge Mobile Full support YesFirefox 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 YesSafari iOS Full support YesSamsung Internet Android Full support Yes
Header names returned in all lower caseChrome Full support YesEdge No support NoFirefox Full support 64IE No support NoOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesEdge Mobile No support NoFirefox Android Full support 64Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support
No support  
No support
See implementation notes.
See implementation notes.

See also

Etiquetas y colaboradores del documento

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