XMLHttpRequest: readyState property
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Note: This feature is available in Web Workers, except for Service Workers.
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, all redirects (if any) have been followed and the response headers have been received.
- LOADING
-
Response's body is being received. If
responseTypeis "text" or empty string,responseTextwill 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.
Example
const 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 = () => {
console.log("LOADING", xhr.readyState); // readyState will be 3
};
xhr.onload = () => {
console.log("DONE", xhr.readyState); // readyState will be 4
};
xhr.send(null);
Specifications
| Specification |
|---|
| XMLHttpRequest # states |
Browser compatibility
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readyState
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Legend
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