Navigation bar that becomes fixed once it reaches the top. Goes from 'chill' to 'fixed.' Also adds an "active" class to nav anchors.

chill-fixed-nav

var lastId,
    scrollNav = $("#fixedMenu"),
    menuItems = scrollNav.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;
    $('html, body').stop().animate({
        scrollTop: offsetTop+10
    }, 300 ,'easeInOutExpo');
    e.preventDefault();
  });

  $(window).scroll(function(){
    var scrollTop = $(window).scrollTop();

    if(scrollTop > 130){
      scrollNav.removeClass('chill').addClass('fixed');
    } else if (scrollTop < 130){
      scrollNav.removeClass('fixed').addClass('chill');
    }

    // Get id of current scroll item
     var cur = scrollItems.map(function(){
      if ($(this).offset().top < scrollTop) {
        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");
     }
  });