原生JavaScript实现网页滑动解锁功能

<!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>yihaomen.com js滑屏解锁</title>
<style type="text/css"> 
#slider_comment{position:relative;width:426px;height:640px;margin:10px auto;}
#lock{width:200px;height:30px;border:1px dashed #ccc;line-height:30px;}
#lock span{position:absolute;width:45px;height:30px;cursor:pointer;background:url(img/arrow.png) no-repeat;}
</style>
<script type="text/javascript"> 
window.onload = function ()
{
  var slider_comment = document.getElementById("slider_comment");
  var oLock = document.getElementById("lock");
  var oBtn = oLock.getElementsByTagName("span")[0];
  var comment=document.getElementById('comment');
  var disX = 0;
  var maxL = oLock.clientWidth - oBtn.offsetWidth;  
  oBtn.onmousedown = function (e)
  {
    var e = e || window.event;
    disX = e.clientX - this.offsetLeft;
    document.onmousemove = function (e)
    {
      var e = e || window.event;
      var l = e.clientX - disX;
      l < 0 && (l = 0);
      l > maxL && (l = maxL);      
      oBtn.style.left = l + "px";      
      oBtn.offsetLeft == maxL && (comment.style.display="block",oLock.innerHTML = "请输入评论内容");
      return false;
    };
    document.onmouseup = function ()
    {
      document.onmousemove = null;
      document.onmouseup = null;
      oBtn.releaseCapture && oBtn.releaseCapture();
      oBtn.offsetLeft > maxL / 2 ?
        startMove(maxL, function ()
        {
          comment.style.display="block";
          oLock.innerHTML = "请输入评论内容";
          oLock.style.display = "block";
        }) :
        startMove(0)
    };
    this.setCapture && this.setCapture();
    return false
  };
  function startMove (iTarget, onEnd)
  {
    clearInterval(oBtn.timer);
    oBtn.timer = setInterval(function ()
    {
      doMove(iTarget, onEnd)
    }, 30)
  }
  function doMove (iTarget, onEnd)
  {
    var iSpeed = (iTarget - oBtn.offsetLeft) / 5;
    iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);
    iTarget == oBtn.offsetLeft ? (clearInterval(oBtn.timer), onEnd && onEnd()) : oBtn.style.left = iSpeed + oBtn.offsetLeft + "px"
  }
};
</script>
</head>
<body>
<div id="slider_comment">
<div id="lock"><span></span></div>
<div id="comment" style="width:500px;height:200px;display:none;">
  <textarea id="comment_text" rows=5 style="width:500px;height:200px;border:1px solid #ccc;"></textarea>
</div>
</div>
</body>
</html>