JavaScript实现登录窗口的拖拽

<!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>

    * {margin: 0; padding: 0; }

    body, textarea, select, input, button {font-size: 12px; color: #fff; font-family: Arial, Helvetica, sans-serif; -webkit-text-size-adjust: none;}

    .fl-l{float: left;}

    .fl-r{float: right;}

    #dialog{

      position: absolute;

      top: 200px;

      left: 400px;

      width: 400px;

      height: 200px;

      background-color: #eaf6db;

      border: 1px solid lightslategray;

    }

    .dialog-title{

      height: 40px;

      line-height: 40px;

      background-color: #3a3333;

      cursor: move;

    }

    .login, .close{

      display: inline-block;

      margin: 0 15px;

    }

  </style>

</head>

<body>

  <div id="dialog">

    <div id="dialog-title" class="dialog-title">

      <span class="fl-l login">登录</span>

      <span class="fl-r close">X</span>

    </div>

  </div>

  <script>

    // 获取DOM元素

    var dialogTitle = document.getElementById('dialog-title')

    var dialog = document.getElementById('dialog')

    // 初始化鼠标默认位置

    var disX = 0, disY = 0

    // 添加鼠标按下事件

    dialogTitle.onmousedown = function(e) {

      var e = e || event

      // 计算鼠标距离弹出框内的位置

      disX = e.clientX - dialog.offsetLeft          // 鼠标相对于浏览器窗口左上角的横向距离 - 弹出框距离页面左上角的横向偏移距离

      disY = e.clientY - dialog.offsetTop           // 鼠标相对于浏览器窗口左上角的纵向距离 - 弹出框距离页面左上角的纵向偏移距离

      // 点击弹出框后拖动鼠标，移动弹出框

      document.onmousemove = function(e) {

        var e = e || event

        // 弹出框dialog距离窗口左上角的水平和纵向距离

        var currentDialogDisX = e.clientX - disX

        var currentDialogDisY = e.clientY - disY

        if(currentDialogDisX < 0) { // 弹出框紧贴窗口左边的情况

          currentDialogDisX = 0

        } else if(currentDialogDisX > document.documentElement.clientWidth - dialog.offsetWidth) { // 弹出框紧贴窗口右边的情况

          currentDialogDisX = document.documentElement.clientWidth - dialog.offsetWidth

        }

        if(currentDialogDisY < 0) { // 弹出框紧贴窗口上边的情况

          currentDialogDisY = 0

        } else if(currentDialogDisY > document.documentElement.clientHeight - dialog.offsetHeight) { // 弹出框紧贴窗口下边的情况

          currentDialogDisY = document.documentElement.clientHeight - dialog.offsetHeight

        }

        // 当鼠标移动时改变弹出框的位置

        dialog.style.left = currentDialogDisX + 'px'

        dialog.style.top = currentDialogDisY + 'px'

      }

      // 当点击鼠标拖动弹出框，抬起鼠标时

      document.onmouseup = function() {

        // 清除弹出框的移动事件及本身

        document.onmousemove = null

        document.onmouseup = null

      }

      // 阻止默认事件，如果不加这个阻止默认事件，在 firefox 下会有一个获取焦点的光标一直在闪动，在3.0及以下会出现拖动出现重影的情况

      return false

    }

  </script>

</body>

</html>
巴特西

JavaScript实现登录窗口的拖拽

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