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. |
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);