元素的拖拽移动（UI实例）

原文链接：https://www.jq22.com/webqd4400

Html

<div id="box"></div>

Css

body,html {
	overflow:hidden;
}
#box {
	position:absolute;
	top:0;
	left:0;
	width:100px;
	height:100px;
	background:pink;
	cursor:move;
}

```

Js

var oBox = document.getElementById('box');
move(oBox)

function move(obj) {
    obj.onmousedown = function(e) { //鼠标按下事件
        e = e || window.event; //事件对象
        var x_down = e.clientX; //鼠标按下X的坐标
        var y_down = e.clientY; //鼠标按下Y的坐标
        var leftDown = this.offsetLeft; //获取盒子的初始left值
        var topDown = this.offsetTop; //获取盒子的初始top值
        document.onmousemove = function(e) { //鼠标移动事件
            e = e || window.event;
            var x_move = e.clientX; //鼠标移动X的坐标
            var y_move = e.clientY; //鼠标移动Y的坐标
            //移动的坐标减去按下的坐标 = 移动的距离
            var x_now = x_move - x_down;
            var y_now = y_move - y_down;
            //赋值给left和top
            obj.style.top = topDown + y_now + 'px';
            obj.style.left = leftDown + x_now + 'px';
        }
        document.onmouseup = function() { //鼠标抬起事件
            //清除移动和抬起事件
            this.onmousemove = this.onmouseup = null
        }
        return false //阻止默认事件
    }
}