onDOMReady

function onDOMReady(fn, ctx) {
   var ready, timer;
   var onChange = function(e) {
         if (e && e.type == "DOMContentLoaded") {
            fireDOMReady();
         } else if (e && e.type == "load") {
            fireDOMReady();
         } else if (document.readyState) {
            if ((/loaded|complete/).test(document.readyState)) {
               fireDOMReady();
            } else if ( !! document.documentElement.doScroll) {
               try {
                  ready || document.documentElement.doScroll('left');
               } catch (e) {
                  return;
               }
               fireDOMReady();
            }
         }
      };
   var fireDOMReady = function() {
         if (!ready) {
            ready = true;
            fn.call(ctx || window);
            if (document.removeEventListener) document.removeEventListener("DOMContentLoaded", onChange, false);
            document.onreadystatechange = null;
            window.onload = null;
            clearInterval(timer);
            timer = null;
         }
      };
   if (document.addEventListener) document.addEventListener("DOMContentLoaded", onChange, false);
   document.onreadystatechange = onChange;
   timer = setInterval(onChange, 5);
   window.onload = onChange;
};