JavaScript abandonment - Optimization option or less expensive features

Question

I have this code and it works exactly the way I want. The menu bar is at the top and recognizes the section in which it is located. You can click links in the yellow menu to navigate between sections.

• http://jsfiddle.net/spadez/2atkZ/9/

• http://jsfiddle.net/spadez/2atkZ/9/embedded/result/

  $ (function () {

  var $select = $('#select');
  var $window = $(window);
  var isFixed = false;
  var init = $select.length ? $select.offset().top : 0;
  
  $window.scroll(function () {
      var currentScrollTop = $window.scrollTop();
      if (currentScrollTop > init && isFixed === false) {
          isFixed = true;
          $select.css({
              top: 0,
              position: 'fixed'
          });
          $('body').css('padding-top', $select.height());
      } else if (currentScrollTop <= init) {
          isFixed = false;
          $select.css('position', 'relative');
          $('#select span').removeClass('active');
          $('body').css('padding-top', 0);
      } 
  
  
      //active state in menu
      $('.section').each(function(){
          var eleDistance = $(this).offset().top;
          if (currentScrollTop >= eleDistance-$select.outerHeight()) {
              var makeActive = $(this).attr('id');
              $('#select span').removeClass('active');
              $('#select span.' + makeActive).addClass('active');
          }
      });
  });
  
  $(".nav").click(function (e) {
      var divId = $(this).data('sec');
      $('body').animate({
          scrollTop: $(divId).offset().top - $select.height()
      }, 500);
  });
  

  });

However, the code itself becomes pretty weak as soon as you start putting any content into fields. I wondered if it was possible to optimize the code and make it a little smoother.

Answer 1

, ( ) ( ), .

, , - ( ).