////js代码说明：        ////currentMoveObj ：全局对象，记录当前拖拽的那个对象        ////var relLeft;：鼠标按下时的横坐标        ////var relTop;鼠标按下时的纵坐标  

<script type="text/javascript">    var currentMoveObj = null;    var relLeft;    var relTop;         ////summary    ////当按下鼠标时，记录当前点击的坐标，记录当前拖拽的对象    function mouseDown(obj)    {    currentMoveObj =obj;    currentMoveObj.setCapture();    currentMoveObj.style.position = "absolute";    relLeft = event.x - currentMoveObj.style.pixelLeft;    relTop = event.y - currentMoveObj.style.pixelTop;    }     /////当鼠标松开时，当前拖拽对象置空    window.document.attachEvent    ('onmouseup',function()    {    currentMoveObj.releaseCapture();    currentMoveObj = null;    });     ////拖拽时，始终更新当前拖拽对象的坐标即可    function mouseMove()    {    if(null != currentMoveObj)    {    currentMoveObj.style.pixelLeft = event.x - relLeft;    currentMoveObj.style.pixelTop = event.y - relTop;    }    }          ////为每一个TABLE对象注册mousedown和mousemove事件    var elements = document.getElementsByTagName("table");    window.onload=function () {    for(var i = 0;i < elements.length;i ++)    {    var obj = elements[i];    attachDragAction(obj);    }    };         function attachDragAction(obj) {    obj.onmousedown= function(){ mouseDown(obj)};    obj.onmousemove= function(){ mouseMove()};    }    </script> 

    <p>JS拖拽</p>        </body>        </html>