【toggle】
<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-1.8.3.js'></script>
<script type='text/javascript'>
$(window).load(function(){
$(document).ready(function () {
$("#needle").click(function () {
$("#leftmenu").toggle();
});
});
});
</script>
</head>
<body>
<div id="container">
<div id="leftmenu">left menu content</div>
<div id="needle">click here</div>
</div>
</body>
</html>
