假如dropdownlist的引用为obj
var t = obj.offsetTop + obj.offsetHeigth;
var l = obj.offsetLeft;
while( obj = obj.offsetParent )
{
   t+=obj.offsetTop;
   l+=obj.offsetLeft;
}OK,t和l的值就是你要找的值了

解决方案 »

  1.   

    <body>           <input type="text" id="txt1" style="background:#eeeeee;position:absolute;top:100;left:100;"/>
                <div id="h1" style="display: none; border: 1px solid #0000ff; overflow: hidden; height: 320px; width:190px;position: absolute; background-color: #ff0000;">
                    
                            <ol>
                                <li>北京</li>
                                <li>天津</li>
                                <li>上海</li>
                                <li>重庆</li>
                                <li>河北</li>
                                <li>河南</li>
                                <li>山东</li>
                                <li>山西</li>
                                <li>江西</li>
                                <li>江苏</li>
                                <li>浙江</li>
                                <li>内蒙古</li>
                            </ol>
                            </div>
                       
    <script type="text/javascript">
    <!--
     var h1=document.getElementById("h1");
     var txt1=document.getElementById("txt1");
     function init(){
     
     h1.style.display=="block"?h1.style.display="none":h1.style.display="block";
     h1.style.left=txt1.offsetLeft;
     h1.style.top=txt1.offsetTop+txt1.offsetHeight;
    }
    txt1.onclick=init;//-->
    </script>
     </body>