JavaScript实现鼠标悬停指定Div时禁止页面滚动

#wrap {
  position:absolute;
  top:200px;
  background:#000000;
  font-size: 40px;
  width:50vw;
  text-align: center;
  color: #ffffff;
  line-height: 300px;
  height:300px;
}

<div id="wrap">
 鼠标移动进入该区域，页面禁止滚动
</div>

window.onload = function () {
  for (i = 0; i < 50; i++) {
  var x = document.createElement('div');
  x.innerHTML = "test<br/>";
  document.body.appendChild(x);
  }
 
  function $(x) {
  return document.getElementById(x);
  };
  $("wrap").onmousewheel = function scrollWheel(e) {
  var sl;
  e = e || window.event;
  if (navigator.userAgent.toLowerCase().indexOf('msie') >= 0) {
   event.returnValue = false;
  } else {
   e.preventDefault();
  };
  };
  if (navigator.userAgent.toLowerCase().indexOf('firefox') >= 0) {
  //firefox支持onmousewheel
  addEventListener('DOMMouseScroll',
   function (e) {
   var obj = e.target;
   var onmousewheel;
   while (obj) {
    onmousewheel = obj.getAttribute('onmousewheel') || obj.onmousewheel;
    if (onmousewheel) break;
    if (obj.tagName == 'BODY') break;
    obj = obj.parentNode;
   };
   if (onmousewheel) {
    if (e.preventDefault) e.preventDefault();
    e.returnValue = false; //禁止页面滚动
    if (typeof obj.onmousewheel != 'function') {
    //将onmousewheel转换成function
    eval('window._tmpFun = function(event){' + onmousewheel + '}');
    obj.onmousewheel = window._tmpFun;
    window._tmpFun = null;
    };
    // 不直接执行是因为若onmousewheel(e)运行时间较长的话，会导致锁定滚动失效，使用setTimeout可避免
    setTimeout(function () {
     obj.onmousewheel(e);
    },
    1);
   };
   },
   false);
  };
}