XMLHttpRequest.readyState

The XMLHttpRequest.readyState property returns the state an XMLHttpRequest client is in. An XHR client exists in one of the following states:

Value State Description
0 UNSENT Client has been created. open() not called yet.
1 OPENED open() has been called.
2 HEADERS_RECEIVED send() has been called, and headers and status are available.
3 LOADING Downloading; responseText holds partial data.
4 DONE The operation is complete.
UNSENT
The XMLHttpRequest client has been created, but the open() method hasn't been called yet.
OPENED
open() method has been invoked. During this state, the request headers can be set using the setRequestHeader() method and the send() method can be called which will initiate the fetch.
HEADERS_RECEIVED
send() has been called and the response headers have been received.
LOADING
Response's body is being received. If responseType is "text" or empty string, responseText will have the partial text response as it loads.
DONE
The fetch operation is complete. This could mean that either the data transfer has been completed successfully or failed.

The state names are different in Internet Explorer. Instead of UNSENT, OPENED, HEADERS_RECEIVED, LOADING and DONE, the names READYSTATE_UNINITIALIZED (0), READYSTATE_LOADING (1), READYSTATE_LOADED (2), READYSTATE_INTERACTIVE (3) and READYSTATE_COMPLETE (4) are used.

Example

var xhr = new XMLHttpRequest();
console.log('UNSENT', xhr.readyState); // readyState will be 0

xhr.open('GET', '/api', true);
console.log('OPENED', xhr.readyState); // readyState will be 1

xhr.onprogress = function () {
    console.log('LOADING', xhr.readyState); // readyState will be 3
};

xhr.onload = function () {
    console.log('DONE', xhr.readyState); // readyState will be 4
};

xhr.send(null);

Specifications

Specification Status Comment
XMLHttpRequest Living Standard WHATWG living standard

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 1 (Yes) 1.0 (1.7 or earlier)[1] 7 (Yes) 1.2
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support ? 1.0 (Yes) (Yes) ? ? ?

Document Tags and Contributors

 Contributors to this page: erikadoyle, jsx, jcanepa
 Last updated by: erikadoyle,