鼠标拖拽窗口案例--- # 主题列表：juejin, github, smartblue, cyanosis, chan

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .nav {
            height: 30px;
            background: #036663;
            border-bottom: 1px solid #369;
            line-height: 30px;
            padding-left: 30px;
        }

        .nav a {
            color: #fff;
            text-align: center;
            font-size: 14px;
            text-decoration: none;

        }

        .d-box {
            width: 400px;
            height: 300px;
            border: 5px solid #eee;
            box-shadow: 2px 2px 2px 2px #666;
            position: absolute;
            top: 40%;
            left: 40%;
            background-color: white;

            /* 不让文字被选中 */
            -webkit-user-select:none;
            -moz-user-select:none;
            -ms-user-select:none;
            user-select:none;
        }

        .hd {
            width: 100%;
            height: 25px;
            background-color: #7c9299;
            border-bottom: 1px solid #369;
            line-height: 25px;
            color: white;
            cursor: move;
        }

        #box_close {
            float: right;
            cursor: pointer;
        }
    </style>
</head>
<body>
<div class="nav">
    <a href="javascript:;" id="register">注册信息</a>
</div>
<div class="d-box" id="d_box">
    <div class="hd" id="drop">注册信息 (可以拖拽)
        <span id="box_close">【关闭】</span>
    </div>
    <div class="bd"></div>
</div>
<script src="common.js"></script>
<script>
    // 获取元素
    var box = document.getElementById("d_box");
    var drop = document.getElementById("drop");
    var close = document.getElementById("box_close");

    // 给 drop 添加鼠标按下事件，在内部继续绑定一个鼠标移动事件
    drop.onmousedown = function (e) {
        e = e || window.event;
        // 记忆鼠标按下时，鼠标在父盒子内部的间距
        var l = e.pageX - box.offsetLeft;
        var t = e.pageY - box.offsetTop;
        // 鼠标移动事件
        drop.onmousemove = function (e) {
            e = e || window.event;
            // 鼠标移动过程中，可以计算 box 的 left 和 top
            var nowleft = e.pageX - l;
            var nowtop = e.pageY - t;
            // 赋值给 box 的样式属性
            box.style.left = nowleft + "px";
            box.style.top = nowtop + "px";
        };
    };

    // 鼠标弹起事件
    drop.onmouseup = function () {
        drop.onmousemove = null;
    };

    // 点击 关闭 box
    close.onclick = function () {
        box.style.display = "none";
    };
</script>
</body>
</html>