jQuery Receding Menu

recedingMenu.js

//jQuery to retract a menu on scroll down, and show on scroll up, in 11 SLOC
var menuSelector = '.menuClass #menuId';
var lastScrollTop = 0;
$(window).scroll(function(event){
  var st = $(this).scrollTop();
  if (st > lastScrollTop){
    $(menuSelector).slideUp(400,'easeOutCirc');
  } else {
    $(menuSelector).slideDown(400,'easeOutCirc');
  }
  lastScrollTop = st;
});