table 表头固定

<html>
<head>
<title>Test</title>
<style type="text/css">
  .divClass{
    height:400px;
    width:25%;
    overflow:auto;
  }
  .divHeadClass{
    overflow:hidden;
  }
</style>
</head>
<body>
<div id="htmlDivID" class="divClass">
<table style="word-break: break-all;background-color:#7f9db9;" border="0" cellspacing="1" cellpadding="0" >
    <thead>
        <tr style="background-color:#dfdfdf;">
            <th width="20%" rowspan="1" colspan="1">Head</th>
            <th width="5%" rowspan="1" colspan="1">Count</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td width="20%" rowspan="1">head0</td>
            <td width="5%" rowspan="1">0</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head50</td>
            <td width="5%" rowspan="1">50</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head05</td>
            <td width="5%" rowspan="1">05</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head40</td>
            <td width="5%" rowspan="1">40</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head04</td>
            <td width="5%" rowspan="1">04</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head70</td>
            <td width="5%" rowspan="1">70</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head07</td>
            <td width="5%" rowspan="1">07</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head10</td>
            <td width="5%" rowspan="1">01</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head110</td>
            <td width="5%" rowspan="1">011</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head02</td>
            <td width="5%" rowspan="1">02</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head03</td>
            <td width="5%" rowspan="1">03</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head066</td>
            <td width="5%" rowspan="1">066</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head660</td>
            <td width="5%" rowspan="1">60</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head055</td>
            <td width="5%" rowspan="1">055</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head0</td>
            <td width="5%" rowspan="1">0</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head0</td>
            <td width="5%" rowspan="1">0</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head022</td>
            <td width="5%" rowspan="1">022</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head220</td>
            <td width="5%" rowspan="1">220</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head055</td>
            <td width="5%" rowspan="1">055</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head034</td>
            <td width="5%" rowspan="1">034</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head023</td>
            <td width="5%" rowspan="1">023</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head021</td>
            <td width="5%" rowspan="1">021</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head210</td>
            <td width="5%" rowspan="1">210</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head012</td>
            <td width="5%" rowspan="1">012</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head120</td>
            <td width="5%" rowspan="1">120</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head0111</td>
            <td width="5%" rowspan="1">0111</td>
        </tr>
        <tr>
            <td width="20%" rowspan="1">head1110</td>
            <td width="5%" rowspan="1">1110</td>
        </tr>
    </tbody>
</table>
</div>
</body>
<script language="javascript">
    window.onload = function(){
        //获得存放表格的DIV
        var htmlDivDom = document.getElementById("htmlDivID");
        //获得表格的头部的偏移高度
        var theadHeight = htmlDivDom.children[0].children[0].offsetHeight;
        //创建可见的头部DIV
        var divHeadDom = document.createElement("<div class=\"divHeadClass\"></div>");
        //将创建的头部添加到表格DIV的前面
        htmlDivDom.parentNode.insertBefore(divHeadDom,htmlDivDom);
        //并设置其高度为表格头部的偏移高度
        divHeadDom.style.height = theadHeight;
        //克隆表格
        var htmlDivCloneDom = htmlDivDom.children[0].cloneNode(true);
        //将克隆表格添加到头部DIV中
        divHeadDom.appendChild(htmlDivCloneDom);
        //设置表格的顶边距
        htmlDivDom.children[0].style.marginTop = - theadHeight;
        //设置头部DIV的宽度：由表格DIV的偏移宽度-滚动条的宽度
        if(htmlDivDom.scrollHeight > htmlDivDom.clientHeight){
            var scrollWidth = getScrollWidth();
            divHeadDom.style.width = htmlDivDom.offsetWidth - scrollWidth;
        }else{
            divHeadDom.style.width = htmlDivDom.offsetWidth;
        }
        var rows = htmlDivDom.children[0].children[1].getElementsByTagName("tr");
        for(var i =0,len=rows.length;i < len;i++){
            if(i % 2 == 0){
                rows[i].style.backgroundColor = "#f9f9f9";
            }else{
                rows[i].style.backgroundColor = "#e5f1ff";

            }
        }
    }

    //创建一个DIV，添加到页面中，先得到没有滚动条的宽度，再得到有滚动条的宽度，两者的差就是滚动条的宽度
    function getScrollWidth(){
        var divDom = document.createElement("div");
        divDom.style.cssText = "position:absolute;top:-1000;height:100px;width:100px;overflow:hidden;";
        var noScrollWidth = document.body.appendChild(divDom).clientWidth;
        divDom.style.overflow = "scroll";
        var scrollWidth = divDom.clientWidth;
        return noScrollWidth - scrollWidth;
    }
</script>
</html>