js实现对象的拖曳

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="__mouseMoveDrop.aspx.cs" Inherits="__mouseMoveDrop" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript">
        var x, y, z, down = false, obj
        function init() {
            obj = event.srcElement     //事件触发对象
            obj.setCapture()            //设置属于当前对象的鼠标捕捉
            z = obj.style.zIndex          //获取对象的z轴坐标值
            //设置对象的z轴坐标值为100，确保当前层显示在最前面
            obj.style.zIndex = 100
            x = event.offsetX   //获取鼠标指针位置相对于触发事件的对象的X坐标
            y = event.offsetY   //获取鼠标指针位置相对于触发事件的对象的Y坐标
            down = true         //布尔值，判断鼠标是否已按下，true为按下，false为未按下
        }

        function moveit() {
            //判断鼠标已被按下且onmouseover和onmousedown事件发生在同一对象上
            if (down && event.srcElement == obj) {
                with (obj.style) {
                    /*设置对象的X坐标值为文档在X轴方向上的滚动距离加上当前鼠标指针相当于文档对象的X坐标值减鼠标按下时指针位置相对于触发事件的对象的X坐标*/

                    posLeft = document.body.scrollLeft + event.x - x
                    /*设置对象的Y坐标值为文档在Y轴方向上的滚动距离加上当前鼠标指针相当于文档对象的Y坐标值减鼠标按下时指针位置相对于触发事件的对象的Y坐标*/
                    posTop = document.body.scrollTop + event.y - y
                }
            }
        }

        function stopdrag() {
            //onmouseup事件触发时说明鼠标已经松开，所以设置down变量值为false
            down = false
            obj.style.zIndex = z       //还原对象的Z轴坐标值
            obj.releaseCapture() //释放当前对象的鼠标捕捉
        }

    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
<div onmousedown="init()" onmousemove="moveit()" onmouseup="stopdrag()" style="position:absolute;left:20;top:190;100;height:150;border:1px solid #000000;z-index:1;background:#eeeeee">Layer 1</div>
<div onmousedown="init()" onmousemove="moveit()" onmouseup="stopdrag()" style="position:absolute;left:60;top:10;100;height:150;border:1px solid #000000;z-index:2;background:#eeeeee">Layer 2</div>
<div onmousedown="init()" onmousemove="moveit()" onmouseup="stopdrag()" style="position:absolute;left:100;top:90;100;height:150;border:1px solid #000000;z-index:3;background:#eeeeee">Layer 3</div>


    </div>
    </form>
</body>
</html>

第二种方式：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>

<body>
<div id="f" style="position: absolute;  200px; height: 150px; background-color: #ccc; top: 150px; left: 200px; z-index: 101; border: solid 1px blue;">
  <div id="title" style="background-color: Blue; cursor: move; height: 20px; color: #fff;font-size: 13px; padding-top: 5px; padding-left: 10px;"> 拖动层 </div>
  </div>
<script type="text/javascript">
var posX;
var posY;
fdiv = document.getElementById("f");
document.getElementById("title").onmousedown=function(e)
{
  if(!e) e = window.event; //如果是IE
  posX = e.clientX - parseInt(fdiv.style.left);
  posY = e.clientY - parseInt(fdiv.style.top);
  document.onmousemove = mousemove;
}
document.onmouseup = function()
{
  document.onmousemove = null;
}
function mousemove(ev)
{
  if(ev==null) ev = window.event;//如果是IE
  fdiv.style.left = (ev.clientX - posX) + "px";
  fdiv.style.top = (ev.clientY - posY) + "px";
}
</script>

</body>
</html>

原文地址：https://www.cnblogs.com/quanhai/p/1727104.html