Debounce jquery scroll events

Question

I just have a general question about debouncing. I have three menus at different positions on the page that when they reach a position 85px from the top of the window on scr

Answer 1

For this case, I think it's really a matter of preference. Take a look at how the site responds in your given situation, and make adjustments if you feel the user experience is negatively affected. I tend to throttle/debounce scroll events.

There are a few things you can do to speed up your scroll handlers (slightly). If you can use id's, for example, as in jQuery's guide to optimizing selectors, e.g. $('#myElement') is fast because it uses document.getElementById.

More minor adjustments if you're worried about performance: Don't make any calls to adjust css if no call is needed. i.e. if nothing changed since the last time the scroll handler was fired. (See isFixed boolean)

$(function(){
  var OFFSET = 85;
  var WAIT = 10;

  // Check the initial Position of the fixed_nav_container
  var stickyHeaderTop0 = $('.fixed_heading_shop').offset().top;
  var isFixed = false; // assuming that's the right default value

  $(window).scroll(_.throttle(function(){
    if($(window).scrollTop() > stickyHeaderTop0 - OFFSET) {
      if(!isFixed) {
        $('#fixed_heading_shop').css({position: 'fixed', top: OFFSET+'px'});
        $('#ghost_div0').css({display: 'block'});
        isFixed = true;
      }
    }
    else {
      if(isFixed) {
        $('#fixed_heading_shop').css({position: 'relative', top: '0px'});
        $('#ghost_div0').css({display: 'none'});
        isFixed = false;
      }
    }
  }, WAIT));
});

The only repeated call is $(window).scrollTop() and if you can combine all your scroll handlers (3?) then you would only need to make that call once per [throttled] scroll event.