<html>
<head>
<script src="https://libs.baidu.com/jquery/1.10.2/jquery.min.js">
</script>
<script>
$(document).ready(function(){
$(document).ajaxStart(function(){
$("#wait").css("display","block");
});
$(document).ajaxComplete(function(){
$("#wait").css("display","none");
});
$("button").click(function(){
$("#txt").load("demo_ajax_load.php");
});
});
</script>
</head>
<body>
<div id="txt"><h2>Let AJAX change this text</h2></div>
<button>Change Content</button>
<div id="wait" style="display:none;width:69px;height:89px;border:1px solid black;position:absolute;top:50%;left:50%;padding:2px;"><img src="/demo/demo_wait.gif" width="64" height="64"><br>Loading..</div>
</body>
</html>