Dynamic background displayer

fully.js

window.fully = (function(win, doc) {
  function viewer(options) {
    win._cb = function(obj) {
      var image = doc.getElementById(options.elementId);
      image.src = '//www.bing.com' + obj.query.results.json.images.url;
      if (image.complete) {
        addClassName(image, 'active', true);
      } else {
        image.onload = function() {
          addClassName(image, 'active', true);
        };
      }
    }
    injectScript('//query.yahooapis.com/v1/public/yql?q=select%20*%20from%20json%20where%20url%3D%22http%3A%2F%2Fwww.bing.com%2FHPImageArchive.aspx%3Fformat%3Djs%26idx%3D0%26n%3D1%26mkt%3Den-US%22&format=json&callback=_cb');
  }

  function player(options) {
    var tv;
    var video = doc.getElementById(options.elementId);
    var screen = video.parentNode;
    var videos = options.videos;

    win.onresize = vidRescale;
    win.onYouTubePlayerAPIReady = function() {
      tv = new YT.Player(options.elementId, {
        events: {
          onReady: onPlayerReady,
          onStateChange: onPlayerStateChange
        },
        playerVars: {
          autoplay: 0, autohide: 1, modestbranding: 0, rel: 0, showinfo: 0,
          controls: 0, disablekb: 1, enablejsapi: 0, iv_load_policy: 3
        }
      });
      video = screen.childNodes[1];
      addEvent(video, 'click', function(event) {
        event.stopPropagation();
      });
      vidRescale();
    };

    function onPlayerReady() {
      tv.loadVideoById({
        videoId: videos[Math.floor(Math.random() * (videos.length - 1 + 1))],
        suggestedQuality: 'hd720'
      });
      tv.mute();
    }

    function onPlayerStateChange(e) {
      if (e.data === 1) {
        addClassName(video, 'active', true);
      } else if (e.data === 0) {
        tv.seekTo(0);
      }
    }

    function vidRescale() {
      var w = win.innerWidth + 400;
      var h = win.innerHeight + 400;
      if (w / h > 16 / 9) {
        tv.setSize(w, w / 16 * 9);
      } else {
        tv.setSize(h / 9 * 16, h);
      }
      video.style.left = (win.innerWidth - video.offsetWidth) / 2 + 'px';
    }

    injectScript('//www.youtube.com/player_api');
  }

  function injectScript(c){var a=doc.createElement("script"),b=doc.getElementsByTagName("script")[0];a.async=!0;a.src=c;b.parentNode.insertBefore(a,b)};
  function addClassName(a,c,b) {if(a.className) {var e=a.className.split(" ");if(b) {b=c.toUpperCase();for(var d=0;d<e.length;d++)e[d].toUpperCase()==b&&(e.splice(d,1),d--)}e[e.length]=c;a.className=e.join(" ")}else a.className=c}
  function addEvent(a,c,b) {"object"!=typeof a&&(a=doc.getElementById(a));a&&(a.attachEvent?(a["e"+c+b]=b,a[c+b]=function() {a["e"+c+b](win.event)},a.attachEvent("on"+c,a[c+b])):a.addEventListener(c,b,!1))};

  return function(options) {
    (win.matchMedia
      && win.matchMedia('(max-device-width: 960px)').matches
      || win.screen.width <= 960 ? viewer : player)(options);
  };
})(window, document);