<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-1.9.1.js'></script>
<script type='text/javascript'>
$(window).load(function(){
setTimeout(function() {
$("a#test").trigger('click');
},4000);
$("a").on('click', function(){
$(this).css('font-size', 50)
})
});
</script>
</head>
<body>
<a href="http://www.w3cschool.cn" id="test">click</a>
</body>
</html>