Javascript Throttle

throttle.js

function throttle(fn, ms, scope) {
  var last = 0;
  var fn = function() {
    var now = Date.now();
    if ( now - last > ms ) {
      last = now;
      fn.apply(scope, arguments);
    }
  };
  return scope ? fn.bind(scope) : fn;
}
/*
 ele.addEventListener(
   'scroll',
   throttle(function(ev) {
     // some slow operation where you don't
     // want to use requestAnimationFrame
   }, 1000/30, ele)
  );
*/