tab

<style type="text/css">

.b_on{}
.b_off{}
</style>

<script type="text/javascript">
        function tabit(tabName, btnId, tabNumber, btnClass) {
            for (i = 0; i < tabNumber; i++) {
                document.getElementById(tabName + '_div' + i).style.display = 'none';
                document.getElementById(tabName + '_btn' + i).className = btnClass + 'off';
            }
            document.getElementById(tabName + '_div' + btnId).style.display = 'block';
            document.getElementById(tabName + '_btn' + btnId).className = btnClass + 'on';
        }
</script>

<ul>
     <li class="b_on" >标签3 </li>
</ul>

<div ></div>

<div ></div>

<div ></div>