$(window).scroll(function() {
var swipeHeight = 200;//完全变色高度
var scrollTop = $(document).scrollTop();//页面滚动高度
var x = scrollTop/swipeHeight;
$(".head-bg").css({"opacity":x});
})
$(window).scroll(function() {
var swipeHeight = 200;//完全变色高度
var scrollTop = $(document).scrollTop();//页面滚动高度
var x = scrollTop/swipeHeight;
$(".head-bg").css({"opacity":x});
})
原文：https://www.cnblogs.com/lhj-blog/p/8521525.html