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XMLHttpRequest

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.

EventTarget XMLHttpRequestEventTarget XMLHttpRequest

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.

Note: This feature is available in Web Workers, except for Service Workers

Constructor

XMLHttpRequest()

The constructor initializes an XMLHttpRequest. It must be called before any other method calls.

Instance properties

This interface also inherits properties of XMLHttpRequestEventTarget and of EventTarget.

XMLHttpRequest.readyState Read only

Returns a number representing the state of the request.

XMLHttpRequest.response Read only

Returns an ArrayBuffer, a Blob, a Document, a JavaScript object, or a string, depending on the value of XMLHttpRequest.responseType, that contains the response entity body.

XMLHttpRequest.responseText Read only

Returns a string that contains the response to the request as text, or null if the request was unsuccessful or has not yet been sent.

XMLHttpRequest.responseType

Specifies the type of the response.

XMLHttpRequest.responseURL Read only

Returns the serialized URL of the response or the empty string if the URL is null.

XMLHttpRequest.responseXML Read only

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 Web Workers.

XMLHttpRequest.status Read only

Returns the HTTP response status code of the request.

XMLHttpRequest.statusText Read only

Returns a string containing the response string returned by the HTTP server. Unlike XMLHttpRequest.status, this includes the entire text of the response message ("OK", for example).

Note: According to the HTTP/2 specification RFC 7540, section 8.1.2.4: Response 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.

XMLHttpRequest.timeout

The time in milliseconds a request can take before automatically being terminated.

XMLHttpRequest.upload Read only

A XMLHttpRequestUpload representing the upload process.

XMLHttpRequest.withCredentials

Returns true if cross-site Access-Control requests should be made using credentials such as cookies or authorization headers; otherwise false.

Non-standard properties

XMLHttpRequest.channel Read only

The channel used by the object when performing the request.

XMLHttpRequest.mozAnon Read only

A boolean. If true, the request will be sent without cookie and authentication headers.

XMLHttpRequest.mozSystem Read only

A boolean. If true, the same origin policy will not be enforced on the request.

XMLHttpRequest.mozBackgroundRequest

A boolean. It indicates whether or not the object represents a background service request.

Instance methods

XMLHttpRequest.abort()

Aborts the request if it has already been sent.

XMLHttpRequest.getAllResponseHeaders()

Returns all the response headers, separated by CRLF, as a string, or null if no response has been received.

XMLHttpRequest.getResponseHeader()

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.

XMLHttpRequest.open()

Initializes a request.

XMLHttpRequest.overrideMimeType()

Overrides the MIME type returned by the server.

XMLHttpRequest.send()

Sends the request. If the request is asynchronous (which is the default), this method returns as soon as the request is sent.

XMLHttpRequest.setRequestHeader()

Sets the value of an HTTP request header. You must call setRequestHeader() after open(), but before send().

Events

abort

Fired when a request has been aborted, for example because the program called XMLHttpRequest.abort(). Also available via the onabort event handler property.

error

Fired when the request encountered an error. Also available via the onerror event handler property.

load

Fired when an XMLHttpRequest transaction completes successfully. Also available via the onload event handler property.

loadend

Fired when a request has completed, whether successfully (after load) or unsuccessfully (after abort or error). Also available via the onloadend event handler property.

loadstart

Fired when a request has started to load data. Also available via the onloadstart event handler property.

progress

Fired periodically when a request receives more data. Also available via the onprogress event handler property.

readystatechange

Fired whenever the readyState property changes. Also available via the onreadystatechange event handler property.

timeout

Fired when progress is terminated due to preset time expiring. Also available via the ontimeout event handler property.

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
XMLHttpRequest 1 12 1 7 ≤12.1 3 4.4 18 4 ≤12.1 1 1.0
XMLHttpRequest 1 12 1 7
5Implemented via ActiveXObject('Microsoft.XMLHTTP')
8 1.2 ≤37 18 4 10.1 1 1.0
abort 1 12 1 5 ≤12.1 1.2 4.4 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
authorization_removed_cross_origin No No 111 No No 16.1 No No 111 No 16.1 No
error_event 1 12 1 10 ≤12.1 1.3 ≤37 18 4 ≤12.1 1 1.0
getAllResponseHeaders 1 12
1Starting 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 4.4 18
4Starting 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
1Starting 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 4.4 18
4Starting 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 4.4 18 4 ≤12.1 1 1.0
open 1 12
1Starting 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 4.4 18
4Starting 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
5Implemented via ActiveXObject
≤12.1 1.2 4.4 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 4.4 18 4 10.1 1 1.0
readystatechange_event 1 12 1 5 9 1.2 4.4 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
5Before Internet Explorer 10, the value of XMLHttpRequest.responseText could be read only once the request was complete.
8 1.2 4.4 18 4 10.1 1 1.0
responseType 31 12 6 10 1812–15 5.1 4.4.3 31 50 1812–14 5 2.0
responseURL 37 14 32 No 24 8 37 37 32 24 8 3.0
responseXML 1 12
1Before 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
4Before 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 4.4 18 4 10.1 1 1.0
setAttributionReporting 117 117 No No 103 No 117 117 No No No No
setPrivateToken 117 117 No No 103 No 117 117 No No No No
setRequestHeader 1 12 1 5 8 1.2 4.4 18 4 10.1 1 1.0
status 1 12 1
7Internet Explorer version 5 and 6 supported ajax calls using ActiveXObject()
8 1.2 4.4 18 4 10.1 1 1.0
statusText 1 12 1
7Internet Explorer version 5 and 6 supported ajax calls using ActiveXObject()
≤12.1 1.2 4.4 18 4 ≤12.1 1 1.0
timeout 29 12 12 8 1712–16 7 4.4 29 14 1812–16 7 2.0
timeout_event 29 12 12 8 16 7 4.4 29 14 16 7 1.0
upload 2 12 3.5 10 ≤12.1 4 4.4 18 4 ≤12.1 3 1.0
withCredentials 3 12
3.5Starting 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.
10Internet Explorer versions 8 and 9 supported cross-domain requests (CORS) using XDomainRequest.
12 4 ≤37 18
4Starting 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.
12 3.2 1.0
worker_support 4 12 3.5 10 10.6 4 4 18 4 11 5 1.0

See also

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https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest