scroll-menu.js

var lastId, 
    topMenu = $('.header-min'), 
    topMenuHeight = topMenu.outerHeight() + 50;

	// All list items		
var menuItems = topMenu.find("a"),
	// Anchors corresponding to menu items
		scrollItems = menuItems.map(function() {
				var item = $($(this).attr("href"));
				if (item.length) {
					return item;
				}
		});

// Bind click handler to menu items
// so we can get a fancy scroll animation
	menuItems.click(function(e) {
		var href = $(this).attr("href"),
				offsetTop = href === "#" ? 0 : $(href).offset().top - topMenuHeight + 1;
		$('html, body').stop().animate({
			scrollTop: offsetTop
		}, 300);
		e.preventDefault();
	});

// Bind to scroll
	$(window).scroll(function() {
		// Get container scroll position
		var fromTop = $(this).scrollTop() + topMenuHeight;

		// Get id of current scroll item
		var cur = scrollItems.map(function() {
			if ($(this).offset().top < fromTop)
				return this;
		});
		// Get the id of the current element
		cur = cur[cur.length - 1];
		var id = cur && cur.length ? cur[0].id : "";

		if (lastId !== id) {
			lastId = id;
			// Set/remove active class
			menuItems
					.parent().removeClass("active")
					.end().filter("[href='#" + id + "']").parent().addClass("active");
		}
	});