js拖动div

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        div{
            position: relative;
            border:1px solid red;
            200px;
            height:200px;
        }
    </style>
</head>
<body>
    <div id="dv">
       ddddddd
    </div>

    <script>
        //获取元素
        var dv = document.getElementById('dv');
        var x = 0;
        var y = 0;
        var l = 0;
        var t = 0;
        var isDown = false;
        //鼠标按下事件
        dv.onmousedown = function(e) {
            //获取x坐标和y坐标
            x = e.clientX;
            y = e.clientY;

            //获取左部和顶部的偏移量
            l = dv.offsetLeft;
            t = dv.offsetTop;
            //开关打开
            isDown = true;
            //设置样式  
            dv.style.cursor = 'move';
        }
        //鼠标移动
        window.onmousemove = function(e) {
            if (isDown == false) {
                return;
            }
            //获取x和y
            var nx = e.clientX;
            var ny = e.clientY;
            //计算移动后的左偏移量和顶部的偏移量
            var nl = nx - (x - l);
            var nt = ny - (y - t);

            dv.style.left = nl + 'px';
            dv.style.top = nt + 'px';
        }
        //鼠标抬起事件
        dv.onmouseup = function() {
            //开关关闭
            isDown = false;
            dv.style.cursor = 'default';
        }
    </script>
</body>
</html>
原文地址:https://www.cnblogs.com/huandong963/p/12256017.html