play gifs on facebook

gifbook.js

(function () {
  var debounce = function (fn, d) {
    var t;
    return function () {
      if (t) clearTimeout(t);
      t = setTimeout(fn, d);
    };
  };
  var giffy = function () {
    [].slice.apply(document.querySelectorAll('a')).filter(function (a) {
      var msover = a.getAttribute('onmouseover');
      if (msover && msover.match(/gif/)) a.dispatchEvent(new Event('mouseover'));
      var href = a.getAttribute('href');
      return(href && !!href.match(/gif$/));
    }).forEach(function (a) {
      var img = a.querySelector('img');
      if (img && img.getAttribute('src') != a.getAttribute('href')) {
        img.setAttribute('src', a.getAttribute('href'));
      }
    }); 
  };
  window.addEventListener('scroll', debounce(giffy, 300));
  giffy();
})();