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JavaScript AJAX Basics (retiring) Programming AJAX Check for the correct ready state

Tyler Nilsson
Tyler Nilsson
10,106 Points

I can not figure out how to add an if condition to check for a status change in AJAX, help?

I am trying to add an if condition to check for the '.readyState' of a server change and I don't know what I'm doing wrong here.

app.js
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
  if (xhr.readyState === 400) {
    return xhr.status === 200;
};
xhr.open('GET', 'sidebar.html');
xhr.send();
index.html
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>AJAX with JavaScript</title>
  <script src="app.js"></script>
</head>
<body>
  <div id="main">
    <h1>AJAX!</h1>
  </div>
  <div id="sidebar"></div>
</body>
</html>

1 Answer

James Sedghi
James Sedghi
21,549 Points

Hi,

readyState can have 5 values (0,1,2,3,4). Try changing the xhr.readyState conditional to see if it equals 4 rather than 400:

var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
  if (xhr.readyState === 4) {
    return xhr.status === 200;
};
xhr.open('GET', 'sidebar.html');
xhr.send();