jHeartbeat 是一个jQuery 的插件，用来定时执行某项任务，例如定时向服务器发送请求；定时更新页面元素等等，特别适合用在聊天室开发上。

使用方法：

<script type=”text/javascript” src=”js/jquery.js”></script>
<script type=”text/javascript” src=js/jheartbeat.js”></script>
<script type=”text/javascript”>
 $(document).ready(function(){
 $.jheartbeat.set({
 url: “data.php”, // The URL that jHeartbeat will retrieve
 delay: 1500, // How often jHeartbeat should retrieve the URL
 div_id: “test_div” // Where the data will be appended.
 , function (){
 // Callback Function
 });
 });
 });
</script>