css如何li中选中后加上class属性js控制

<ul>

<li class=""pageson"><span>1</span></li>

<li><span>2</span></li>

<li><span>3</span></li>

<li><span>4</span></li>

<li><span>5</span></li>

</ul>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js" type="text/javascript"></script>

<script>
$(document).ready(function(){
$('ul li').click(function(){
$(this).siblings().removeClass('pageson');
$(this).addClass('pageson');

})

})

</script>