Debounce

debounce.js

function debounce(func, wait, immediate) {
  var timeout;
  return function() {
    var context = this, args = arguments;
    var later = function() {
      timeout = null;
      if (!immediate) func.apply(context, args);
    };
    var callNow = immediate && !timeout;
    clearTimeout(timeout);
    timeout = setTimeout(later, wait);
    if (callNow) func.apply(context, args);
  };
};

example.js

var affix = debounce(function() {
  var scrollPosition = $(window).scrollTop()
    , affixedElement = $('.header--primary');
  if(scrollPosition) {
    affixedElement.addClass('is-affixed');
  } else {
    affixedElement.removeClass('is-affixed');
  }
}, 10);