js实现完美拖拽效果可拖动层与回放拖动规迹并显示拖动距离参数

完美拖拽

html,body{overflow:hidden;}
body,div,h2,p{margin:0;padding:0;}
body{color:#fff;background:#000;font:12px/2 Arial;}
p{padding:0 10px;margin-top:10px;}
span{color:#ff0;padding-left:5px;}
#box{position:absolute;width:300px;height:150px;background:#333;border:2px solid #ccc;top:50%;left:50%;margin:-75px 0 0 -150px;}
#box h2{height:25px;cursor:move;background:#222;border-bottom:2px solid #ccc;text-align:right;padding:0 10px;}
#box h2 a{color:#fff;font:12px/25px Arial;text-decoration:none;outline:none;}

window.onload=function ()
{
var oBox=document.getElementById("box");
var oH2 = oBox.getElementsByTagName("h2")[0];
var oA = oBox.getElementsByTagName("a")[0];
var aSpan = oBox.getElementsByTagName("span");
var disX = disY = 0;
var bDrag = false;
var aPos = [{x:oBox.offsetLeft, y:oBox.offsetTop}]
//鼠标按下, 激活拖拽
oH2.onmousedown = function (event)
{
var event = event || window.event;
bDrag = true;
disX = event.clientX - oBox.offsetLeft;
disY = event.clientY - oBox.offsetTop;
aPos.push({x:oBox.offsetLeft, y:oBox.offsetTop})
this.setCapture && this.setCapture();
return false
};

//拖拽开始
document.onmousemove = function (event)
{
if (!bDrag) return;
var event = event || window.event;
var iL = event.clientX - disX;
var iT = event.clientY - disY;
var maxL = document.documentElement.clientWidth - oBox.offsetWidth;
var maxT = document.documentElement.clientHeight - oBox.offsetHeight;
iL = iL maxL ? maxL : iL;

iT = iT maxT ? maxT : iT;
oBox.style.marginTop = oBox.style.marginLeft = 0;
oBox.style.left = iL + "px";
oBox.style.top = iT + "px";
aPos.push({x:iL, y:iT})
status();
return false
};
//鼠标释放, 结束拖拽
document.onmouseup = window.onblur = oH2.onlosecapture = function ()
{
bDrag = false;
oH2.releaseCapture && oH2.releaseCapture();
status()
};

//回放拖动轨迹
oA.onclick = function ()
{
if (aPos.length == 1) return;
var timer = setInterval(function ()
{
var oPos = aPos.pop();
oPos ? (oBox.style.left = oPos.x + "px", oBox.style.top = oPos.y + "px", status()) : clearInterval(timer)
}, 30);

this.focus = false;//去除链接虚线

return false
};

//阻止冒泡
oA.onmousedown = function (event)
{
(event || window.event).cancelBubble = true
};

//监听状态函数
function status ()
{
aSpan[0].innerHTML = bDrag;
aSpan[1].innerHTML = oBox.offsetTop;
aSpan[2].innerHTML = oBox.offsetLeft
}

//初始调用
status()
};

点击回放拖动轨迹

Drag:

offsetTop:

offsetLeft:

[Ctrl+A 全选 注:如需引入外部Js需刷新才能执行]