html js get the roll axis height

window.onload = function () {
  //接着利用我们自己封装的函数给div绑定事件，
  var oDiv = document.getElementById('div1');
  addEvent(oDiv,'mousewheel',onMouseWheel);
  addEvent(oDiv,'DOMMouseScroll',onMouseWheel);
  // 当滚轮事件发生时，执行onMouseWheel这个函数
  function onMouseWheel() {
    var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;　　//scrollTop就是触发滚轮事件时滚轮的高度}); 

  }
}