Caching layer for Jquery

cacheApp

/*
*
** Tiny lib to make jQuery times faster
** Usage
** app = new 
** app.$('#selector');
*        var app = window._APP = new window.app({
*            // Caching global window and document objects inside the app object
*            "window": window,
*            "document": document,
*            // jQuery
*            "lib": $,
*            // Allow logging
*            "logging": false
*        });
*/
 
;(function(window, document, undefined){
    "use strict";
 
    window.app = window.app || function( settings ) {
        this.window = window;
        this.document = document;
        this.lib = (settings && settings.lib) || window.jQuery;
        this.logging = settings && settings.logging;
        this.appName = settings && settings.appName;
    };
 
    window.app.prototype = {
        _cacheElem: {},
        log: function( msg ) {
            var logStr = this.appName + ": " + msg;
 
            if ( window.console && window.console.log ) {
                window.console.log( logStr );
            }
        },
        // localized selector provided in the app scope
        $: function( elem, fromCache) {
 
            if ( fromCache === false ) {
                this._cacheElem[elem] = this.lib(elem);
            }
 
            if ( this._cacheElem[elem] === undefined ) {
                this._cacheElem[elem] = this.lib(elem);
            }
 
            return this._cacheElem[elem];
        },
 
        // localized selector key, val mapping
        $$: function( key, elem ) {
            if ( !elem ) {
                return this._cacheElem[key];
            }
 
            if ( this._cacheElem[key] === undefined ) {
                this._cacheElem[key] = this.lib(elem);
            }
 
            return this._cacheElem[key];
        }
 
    };
 
})( window, document );
 
var obj = new window.app({ appName: "testapp" });