What is meaning of xhr.readystate===4
JavascriptJqueryAjaxJavascript Problem Overview
Is it right to say that the AJAX call has completed after xhr.readystate===4?
Here it says the state is complete. So what does this complete mean?
Javascript Solutions
Solution 1 - Javascript
An Ajax http request has 5 states as your reference documents:
0 UNSENT open() has not been called yet.
1 OPENED send() 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.
State 4 means that the request had been sent, the server had finished returning the response and the browser had finished downloading the response content. So, it is right to say that the AJAX call has completed.
Solution 2 - Javascript
Yes, it is correct.xhr.readstate===4 means request finished and response is ready. You can refer this for details.
Here is small example:
xmlhttp.open("GET", "test.txt", true);
xmlhttp.onreadystatechange = function() {
if(xmlhttp.readyState==4) {
alert(xmlhttp.responseText);
}
}
xmlhttp.send(null);
The above script makes a GET request for the relative url "text.txt" (relative to the calling page) It provides the function, which checks the readyState property each time it's called and when it has the value 4 - meaning the load is complete, it displays the responseText to the user with an alert.