XMLHttpRequest.readyState property returns the state an XMLHttpRequest client is in. An XHR client exists in one of the following states:
| 值 | 状态 | 描述 |
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. |
The XMLHttpRequest client has been created, but the open() method hasn't been called yet.
send() has been called and the response headers have been received.
responseType
is "text" or empty string,
responseText
will have the partial text response as it loads.
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 versions of Internet Explorer earlier than 11. 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.
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);
| 规范 | 状态 | 注释 |
|---|---|---|
| XMLHttpRequest | 实时标准 | WHATWG (Web 超文本应用程序技术工作组) 实时标准 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
readyState
|
Chrome 1 | Edge 12 | Firefox 1 | IE 7 | Opera 8 | Safari 1.2 | WebView Android 1 | Chrome Android 18 | Firefox Android 4 | Opera Android 10.1 | Safari iOS 1 | Samsung Internet Android 1.0 |
constants
|
Chrome Yes | Edge 12 | Firefox 9 | IE 9 | Opera 12 | Safari Yes | WebView Android Yes | Chrome Android 18 | Firefox Android 9 | Opera Android Yes | Safari iOS ? | Samsung Internet Android 1.0 |
完整支持
兼容性未知
XMLHttpRequest