Show and hide mobile menu on scroll.js

// Show and hide mobile menu on scroll  

$(document).ready(function(){
    var mob_menu = $('.mobile-menu');
    var lastScrollTop = 0;
    $(window).scroll(function(event){
       var st = $(this).scrollTop();
       if (st > lastScrollTop){
        mob_menu.addClass('scroll');
       } else {
            mob_menu.removeClass('scroll');

       }
       lastScrollTop = st;
    });

   });