JavaScript Tutorial

.ajaxStart()

<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
  $(document).ajaxStart(function(){
    $(this).html("<img src='demo_wait.gif'>");
  });
  $("button").click(function(){
    $("div").load("demo_ajax_load.asp");
  });
});
</script>
</head>
<body>
<div><h2>Let AJAX change this text</h2></div>
<button>Change Content</button>
</body>
</html>