jquery - 使用滚动方向去抖动滚动

Question

我正在寻找一种方法来获取去抖动滚动事件的滚动方向。到目前为止，我可以消除滚动，但它不会触发我的条件上/下脚本。

var el = $(window);
            lastY = el.scrollTop();
            el.on('scroll', debounce(function(e) {

            $('body').bind('DOMMouseScroll', function(e){
                 if(e.originalEvent.detail > 0) {
                     //scroll down
                     scrolldown();
                     console.log('Down');
                 }else {
                     //scroll up
                     scrollup();
                     console.log('Up');
                 }
                 //prevent page fom scrolling
                 return false;
             });

             //IE, Opera, Safari
             $('body').bind('mousewheel', function(e){
                 if(e.originalEvent.wheelDelta < 0) {
                     //scroll down
                     scrolldown();
                     console.log('Down');
                 }else {
                     //scroll up
                     scrollup();
                     console.log('Up');
                 }

                 //prevent page fom scrolling
                 return false;
             });

            }, 200));

Answer 1

无法将事件侦听器添加到body此处，因此我将其添加到#wrapper

function debounce(func, wait, immediate) {
  var timeout;
  return function() {
    var context = this,
      args = arguments;
    var later = function() {
      timeout = null;
      if (!immediate) func.apply(context, args);
    };
    var callNow = immediate && !timeout;
    clearTimeout(timeout);
    timeout = setTimeout(later, wait);
    if (callNow) func.apply(context, args);
  };
}

var onScroll = debounce(function(direction) {
  if (direction == false) {
  	console.log('Scrolling down');
  } else {
  	console.log('Scrolling up');
  }
}, 200, true);

$('#wrapper').bind('mousewheel', function(e){
  e.preventDefault();
  var delta;
  if (event.wheelDelta) {
    delta = event.wheelDelta;
  } else {
    delta = -1 * event.deltaY;
  }

  onScroll(delta >= 0);
});

body {
margin: 0;
padding: 0;
}

#wrapper {
min-height: 100vh;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<div id="wrapper"><div>