javascript 在滚动上隐藏/显示标题

Posted 2021-05-04

(function hide_header_on_scroll(){

	var didScroll,
		lastScrollTop = 0,
		delta = 5,
		$navbar = $('#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){
	        $navbar.removeClass('nav-down').addClass('nav-up');
	    } else {
	        if(st + $(window).height() < $(document).height()) {
	            $navbar.removeClass('nav-up').addClass('nav-down');
	        }
	    }
	    
	    lastScrollTop = st;
	}

})();