jQuery ready and bindReady

gistfile1.js

ready: function( fn ) {
    // Attach the listeners
    jQuery.bindReady();
		
    // Add the callback
    readyList.add( fn );
		
    return this;
}

bindReady: function() {
    if ( readyList ) {
        return;
    }
		
    readyList = jQuery.Callbacks( "once memory" );
		
    // Catch cases where $(document).ready() is called after the
    // browser event has already occurred.
    if ( document.readyState === "complete" ) {
        // Handle it asynchronously to allow scripts the opportunity to delay ready
        return setTimeout( jQuery.ready, 1 );
    }
		
    // 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", jQuery.ready, 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", jQuery.ready );
		
        // 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();
        }
    }
}