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$('body').on("mousewheel DOMMouseScroll", function (event) { 
  // chrome & ie || // firefox
  var delta = (event.originalEvent.wheelDelta && (event.originalEvent.wheelDelta > 0 ? 1 : -1)) || (event.originalEvent.detail && (event.originalEvent.detail > 0 ? -1 : 1));  

  if (delta > 0) { 
    // 向上滚动
    console.log('mousewheel top');
  } else if (delta < 0) {
    // 向下滚动
    console.log('mousewheel bottom');
  } 
});