Auto #id query cache (http://jsfiddle.net/leocavalcante/yCxAk/15)

instance.js

(function ( context, undefined ) {
    function instance ( node ) {
        if ( node.id && !global[node.id] )
            global[node.id] = node;
        if ( node.children.length )
            for ( var i = 0, l = node.children.length ; i < l ; i++ )
                instance( node.children[i] );
    }( context );
} ( document.body ));