javascript 滚动时隐藏/显示标题

Posted 2021-05-03

(function handleScroll() {
// Hide Header on on scroll down
var 
	didScroll,
	lastScrollTop,
	delta,
	$navbar = $('.site-header'),
	navbarHeight = $navbar.outerHeight();

$(window).scroll(function(event){
    didScroll = true;
});

setInterval(function() {
    if (didScroll) {
        hasScrolled();
        didScroll = false;
    }
}, 250);

function hasScrolled() {
    var st = $(this).scrollTop();
    
    if(Math.abs(lastScrollTop - st) <= delta)
        return;
    if (st > lastScrollTop && st > navbarHeight){
        $('body').addClass('scroll-down');
    } else {
        if(st + $(window).height() < $(document).height()) {
            $('body').removeClass('scroll-down');
        }
    }
    lastScrollTop = st;
	}
})();