var n=136; $("#test").click(function() { $( this ).css( {"font-size" : n+=10}); });
<script src="http://code.jquery.com/jquery-latest.js"></script> <span id="test">asdasd</span> <script type="text/javascript"> var IntervalId; $("#test").click(function() { var n=2; var a = $( this ); clearInterval(IntervalId); IntervalId=setInterval(function() {a.css( {"font-size" : n+=10});},1000); }); </script>