判断页面滚动方向是一个常见的需求，下面展示一个使用原生JS方式判断页面滚动方向的解决方式。
html
<script src="http://g.tbcdn.cn/tb/kimi/0.0.233/kimi.js"></script>
<body style="height: 6000px;">
<div class="nav" style="position:fixed; top:0;left:0;width: 100%;height: 60px;background-color: pink;"></div>
</body>
js
var $nav = $('.nav');
var $result = $('.result');
//页面滚动监听事件
window.onscroll = function(e){
$result.html('swipeDown');
scrollFunc();
if(scrollDirection == 'down'){
$nav.css({
position: 'absolute'
});
}
else if(scrollDirection == 'up'){
$nav.css({
position: 'fixed'
});
}
}
var scrollAction = {x: 'undefined', y: 'undefined'}, scrollDirection;
//判断页面滚动方向
function scrollFunc() {
if (typeof scrollAction.x == 'undefined') {
scrollAction.x = window.pageXOffset;
scrollAction.y = window.pageYOffset;
}
var diffX = scrollAction.x - window.pageXOffset;
var diffY = scrollAction.y - window.pageYOffset;
if (diffX < 0) {
// Scroll right
scrollDirection = 'right';
} else if (diffX > 0) {
// Scroll left
scrollDirection = 'left';
} else if (diffY < 0) {
// Scroll down
scrollDirection = 'down';
} else if (diffY > 0) {
// Scroll up
scrollDirection = 'up';
} else {
// First scroll event
}
scrollAction.x = window.pageXOffset;
scrollAction.y = window.pageYOffset;
}
github地址
https://github.com/korbinzhao/exercise/blob/master/js-scroll-direction.html
**粗体** _斜体_ [链接](http://example.com) `代码` - 列表 > 引用。你还可以使用@来通知其他用户。