Suppose I have an html code :
PHP Code:
<html>
<
head>
<
script src="includejquery.js"/>
<
script type="text/javascript" src="chat.js"></script>
</head>
<title>Chat</title>
<body onload="process()">
<div id="chatmessages">
</div>
</body>
</html> 
Suppose I have a jQuery code(chat.js) :
Code:
function process(){
    $.get('chat.php', function(data) {
        $("#chatmessages").html(data+"<hr />");
    });
});
As you see its a very simple and basic code to implement chatting.
And I intend to call the function process() every 3 seconds.
What do I do to call the function process() every 3 seconds?