toggleClass()
<!DOCTYPE html>
<html>
<script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
<style type="text/css">
.highlight { background: yellow; }
</style>
<script>
$(function(){
$("#div").on("click", function(){
$(this).toggleClass("highlight");
});
});
</script>
<body>
<div id="div">HELLO</div>
</body>
</html>
