jquery.documentReady.js

/*
  jQuery's document.ready/$(function(){}) should
  you wish to use a cross-browser DOMReady solution 
  without opting for a library.

  Demo: http://jsfiddle.net/9CWtz/

  usage:
  $(function(){
     // your code
  });

  Parts: jQuery project, Diego Perini, Lucent M.
  This version: Addy Osmani
*/
(function (window) {
  // Define a local copy of $
  var $ = function (callback) {
      readyBound = false;
      $.isReady = false;
      if (typeof callback == 'function') {
        DOMReadyCallback = callback;
      }
      bindReady();
    },
    // Use the correct document accordingly with window argument (sandbox)
    document = window.document,
    readyBound = false,
    DOMReadyCallback = function () {},
    // The ready event handler
    DOMContentLoaded;
  // Is the DOM ready to be used? Set to true once it occurs.
  $.isReady = false;
  // Handle when the DOM is ready
  var DOMReady = function () {
      // Make sure that the DOM is not already loaded
      if (!$.isReady) {
        // Make sure body exists, at least, in case IE gets a little overzealous (ticket #5443).
        if (!document.body) {
          setTimeout(DOMReady, 13);
          return;
        }
        // Remember that the DOM is ready
        $.isReady = true;
        // If there are functions bound, to execute
        DOMReadyCallback();
        // Execute all of them
      }
    } // /ready()
  var bindReady = function () {
      if (readyBound) {
        return;
      }
      readyBound = true;
      // Catch cases where $ is called after the
      // browser event has already occurred.
      if (document.readyState === "complete") {
        DOMReady();
      }
      // Mozilla, Opera and webkit nightlies currently support this event
      if (document.addEventListener) {
        // Use the handy event callback
        document.addEventListener("DOMContentLoaded", DOMContentLoaded, false);
        // A fallback to window.onload, that will always work
        window.addEventListener("load", DOMContentLoaded, false);
        // If IE event model is used
      } else if (document.attachEvent) {
        // ensure firing before onload,
        // maybe late but safe also for iframes
        document.attachEvent("onreadystatechange", DOMContentLoaded);
        // A fallback to window.onload, that will always work
        window.attachEvent("onload", DOMContentLoaded);
        // If IE and not a frame
        // continually check to see if the document is ready
        var toplevel = false;
        try {
          toplevel = window.frameElement == null;
        } catch (e) {}
        if (document.documentElement.doScroll && toplevel) {
          doScrollCheck();
        }
      }
    }; // /bindReady()
  // The DOM ready check for Internet Explorer
  var doScrollCheck = function () {
      if ($.isReady) {
        return;
      }
      try {
        // If IE is used, use the trick by Diego Perini
        // http://javascript.nwbox.com/IEContentLoaded/
        document.documentElement.doScroll("left");
      } catch (error) {
        setTimeout(doScrollCheck, 1);
        return;
      }
      // and execute any waiting functions
      DOMReady();
    } // /doScrollCheck()
    // Cleanup functions for the document ready method
  if (document.addEventListener) {
    DOMContentLoaded = function () {
      document.removeEventListener("DOMContentLoaded", DOMContentLoaded, false);
      DOMReady();
    };
  } else if (document.attachEvent) {
    DOMContentLoaded = function () {
      // Make sure body exists, at least, in case IE gets a little overzealous (ticket #5443).
      if (document.readyState === "complete") {
        document.detachEvent("onreadystatechange", DOMContentLoaded);
        DOMReady();
      }
    };
  } // /if()
  // Expose $ to the global object
  window.$ = $;
})(window);