XMLHttpRequest (XHR) objects are used to interact with servers. You can retrieve data from a URL without having to do a full page refresh. This enables a Web page to update just part of a page without disrupting what the user is doing.
XMLHttpRequest is used heavily in AJAX programming.
Despite its name, XMLHttpRequest can be used to retrieve any type of data, not just XML.
If your communication needs to involve receiving event data or message data from a server, consider using server-sent events through the EventSource interface. For full-duplex communication, WebSockets may be a better choice.
Returns a Document containing the response to the request, or null if the request was unsuccessful, has not yet been sent, or cannot be parsed as XML or HTML. Not available in workers.
Returns a DOMString containing the response string returned by the HTTP server. Unlike XMLHttpRequest.status, this includes the entire text of the response message ("200 OK", for example).
Note: According to the HTTP/2 specification (8.1.2.4Response Pseudo-Header Fields), HTTP/2 does not define a way to carry the version or reason phrase that is included in an HTTP/1.1 status line.
Is a boolean value that indicates whether or not cross-site Access-Control requests should be made using credentials such as cookies or authorization headers.
Returns the string containing the text of the specified header, or null if either the response has not yet been received or the header doesn't exist in the response.
Fired when a request has been aborted, for example because the program called XMLHttpRequest.abort(). Also available via the onabort event handler property.
Fired when a request has completed, whether successfully (after load) or unsuccessfully (after abort or error). Also available via the onloadend event handler property.
Implemented via ActiveXObject('Microsoft.XMLHTTP')
8
1.2
1
18
4
10.1
1
1.0
XMLHttpRequest
1
12
1
7
≤12.1
3
1
18
4
≤12.1
1
1.0
abort
1
12
1
5
≤12.1
1.2
1
18
4
≤12.1
1
1.0
abort_event
1
12
3.5
10
≤12.1
1.3
≤37
18
4
≤12.1
1
1.0
error_event
1
12
1
10
≤12.1
1.3
≤37
18
4
≤12.1
1
1.0
getAllResponseHeaders
1
12
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.
5
≤12.1
1.2
1
18
4
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.
≤12.1
1
1.0
getResponseHeader
1
12
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.
5
8
1.2
1
18
4
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.
10.1
1
1.0
load_event
1
12
1
9
≤12.1
1.3
≤37
18
4
≤12.1
1
1.0
loadend_event
18
12
5
10
≤12.1
4
4.4
18
5
≤12.1
3
1.0
loadstart_event
1
12
3.5
10
≤12.1
1.3
1
18
4
≤12.1
1
1.0
open
1
12
1
Starting in Firefox 30, synchronous requests on the main thread have been deprecated due to their negative impact on performance and the user experience. Therefore, the async parameter may not be false except in a Worker.
5
8
1.2
1
18
4
Starting in Firefox 30, synchronous requests on the main thread have been deprecated due to their negative impact on performance and the user experience. Therefore, the async parameter may not be false except in a Worker.
10.1
1
1.0
overrideMimeType
1
12
1
11
5
Implemented via ActiveXObject
≤12.1
1.2
1
18
4
≤12.1
1
1.0
progress_event
1
12
1
10
≤12.1
3
≤37
18
4
≤12.1
1
1.0
readyState
1
12
1
7
8
1.2
1
18
4
10.1
1
1.0
readystatechange_event
1
12
1
5
9
1.2
1
18
4
10.1
1
1.0
response
9
12
6
10
11.6
5.1
3
18
6
12
5
1.0
responseText
1
12
1
5
Before Internet Explorer 10, the value of XMLHttpRequest.responseText could be read only once the request was complete.
8
1.2
1
18
4
10.1
1
1.0
responseType
31
12
6
10
18
12-15
5.1
4.4.3
31
50
18
12-14
5
2.0
responseURL
37
14
32
No
24
8
37
37
32
24
8
3.0
responseXML
1
12
1
Before Firefox 51, an error parsing the received data added a <parsererror> node to the top of the Document and then returned the Document in whatever state it happens to be in. This was inconsistent with the specification. Starting with Firefox 51, this scenario now correctly returns null as per the spec.
7
≤12.1
3
≤37
18
4
Before Firefox 51, an error parsing the received data added a <parsererror> node to the top of the Document and then returned the Document in whatever state it happens to be in. This was inconsistent with the specification. Starting with Firefox 51, this scenario now correctly returns null as per the spec.
≤12.1
1
1.0
send
1
12
1
5
8
1.2
1
18
4
10.1
1
1.0
setRequestHeader
1
12
1
5
8
1.2
1
18
4
10.1
1
1.0
status
1
12
1
7
Internet Explorer version 5 and 6 supported ajax calls using ActiveXObject()
8
1.2
1
18
4
10.1
1
1.0
statusText
1
12
1
7
Internet Explorer version 5 and 6 supported ajax calls using ActiveXObject()
≤12.1
1.2
1
18
4
≤12.1
1
1.0
timeout
29
12
12
8
17
12-16
7
4.4
29
14
18
12-16
7
2.0
timeout_event
29
12
12
8
16
7
4.4
29
14
16
7
1.0
upload
1
12
3.5
10
≤12.1
4
1
18
4
≤12.1
3
1.0
withCredentials
3
12
3.5
Starting with Firefox 11, it's no longer supported to use the withCredentials attribute when performing synchronous requests. Attempting to do so throws an NS_ERROR_DOM_INVALID_ACCESS_ERR exception.
10
Internet Explorer versions 8 and 9 supported cross-domain requests (CORS) using XDomainRequest.
12
4
≤37
18
4
Starting with Firefox 11, it's no longer supported to use the withCredentials attribute when performing synchronous requests. Attempting to do so throws an NS_ERROR_DOM_INVALID_ACCESS_ERR exception.