documentReady

documentReady.js

/*
 * documentReady.js - a cross-browser jQuery core based DOMContentLoaded solution
 * Released under an MIT license
 * Portions: jQuery project, Diego Perini, Lucent M.
 * This version: Addy Osmani, 2012
*/

/*
 * Usage:
   documentReady(function(){
      ...
   });
*/

;(function( window, document, undefined ) {

        var documentReady = function( callback ){
                readyBound = false;
                documentReady.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.
        documentReady.isReady = false;

        // Handle when the DOM is ready
        var DOMReady = function() {
                // Make sure that the DOM is not already loaded
                if ( !documentReady.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
                        documentReady.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 documentReady is called after the
                // browser event has already occurred.
                if ( document.readyState === "complete" ) {
                        DOMReady();
                }

                // Mozilla, Opera and webkit 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 ( documentReady.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();
                        }
                };
        }

        // Expose documentReady to the global object
        window.documentReady = documentReady;
})(window);

documentReady.min.js

//872 bytes

(function(a,b,c){var d=function(a){e=!1,d.isReady=!1,typeof a=="function"&&(f=a),i()},b=a.document,e=!1,f=function(){},g;d.isReady=!1;var h=function(){if(!d.isReady){if(!b.body){setTimeout(h,13);return}d.isReady=!0,f()}},i=function(){if(e)return;e=!0,b.readyState==="complete"&&h();if(b.addEventListener)b.addEventListener("DOMContentLoaded",g,!1),a.addEventListener("load",g,!1);else if(b.attachEvent){b.attachEvent("onreadystatechange",g),a.attachEvent("onload",g);var c=!1;try{c=a.frameElement==null}catch(d){}b.documentElement.doScroll&&c&&j()}},j=function(){if(d.isReady)return;try{b.documentElement.doScroll("left")}catch(a){setTimeout(j,1);return}h()};b.addEventListener?g=function(){b.removeEventListener("DOMContentLoaded",g,!1),h()}:b.attachEvent&&(g=function(){b.readyState==="complete"&&(b.detachEvent("onreadystatechange",g),h())}),a.documentReady=d})(window)

Sample usage: http://jsfiddle.net/fEGgD/1/

Currently tested: Chrome (stable, canary), Safari, FF, Opera. Will test in IE shortly.

@jdalton sure this has been written/solved elsewhere a million times over, but if there are any changes/suggestions you would make on the above, always happy to hear them. Had to put something like this together for a non-jq project recently.