普通のtabバーの切り替えと関数パッケージ

/*                ，                  */
*{margin: 0;padding: 0;list-style: none;outline: none;}
/*     .tab         */
.tab{width: 398px;height: 200px;border: 1px solid #ddd;margin: 100px auto 0;font-family: 'arial';}
.hd{background: #f7f7f7;height: 30px;line-height: 30px;text-align: center;}
.hd ul{width: 400px;margin-left: -1px;}
.hd li{float: left;width: 98px;padding: 0 1px;border-bottom: 1px solid #ddd;}
.hd li.cur{background: #fff;border-bottom-color: transparent;border-left: 1px solid #ddd;border-right: 1px solid #ddd;padding: 0;}
.hd li.cur a{font-size: 14px;font-weight: 600;color: #f40;}
/*    a display:block   li   1px     */
.hd li a{text-decoration: none;color: #666;font-size: 12px;display: block;}
.hd a:hover{text-decoration: none;}
.bd{position: relative;}
.bd li{text-indent: 2em;line-height: 80px;height: 269px;position: absolute;top: 0;left: 0;width: 100%;display: none;}
.bd li.cur{display: block;}

<div class="tab" id='tab'>
    <div class="hd">
        <ul>
            <li><a href="javascript:;">  1</a></li>
            <li><a href="javascript:;">  2</a></li>
            <li><a href="javascript:;">  3</a></li>
            <li><a href="javascript:;">  4</a></li>
        </ul>
    </div>
    <div class="bd">
        <ul>
            <li>    1    </li>
            <li>    2    </li>
            <li>    3    </li>
            <li>    4    </li>
        </ul>
    </div>
</div>

tab('tab'); //     

// tab     
function tab(obj) {
    var tab = document.getElementById(obj);
    var hdlis = tab.children[0].getElementsByTagName('li');
    var bdlis = tab.children[1].getElementsByTagName('li');
    var l = hdlis.length;
    hdlis[0].className = 'cur';
    bdlis[0].className = 'cur';
    for(var i = 0; i < l; i ++) {
        hdlis[i].index = i;
        hdlis[i].onmouseenter = function () {
            for(var i = 0; i < l; i ++) {
                hdlis[i].className = '';
                bdlis[i].className = '';
            }
            this.className = 'cur';
            bdlis[this.index].className = 'cur';
        }
    }
}