what changed from the default

diff

		function diff(defaults, customs, diffs){
		/**
		 * @description
			compare an object against the default returning an object with the differences
			in the customs object separated out in the returned value
			when there are no unique values in the customs object undefined is returned
		 * @returns
			diff value, when no differences undefined, when an object returns object with keys and other values
		 * @example
			usr.diff(defaults, custom);
			usr.diff({a:1,zeb:[7]},{b:2,zeb:[1,2,3]})
			returns {b:2, zeb:[1,2,3]}
		 */
			diffs = diffs || {};

			function diffr(defaults, customs, result){
			// return what's different in customs
				var alt, key, item, ckeys;
				try{
				// only objects have keys
					ckeys = Object.keys( customs );
				}catch(customNotAnObject){
					// customs isn't an object here, compare primitives strictly
					if(defaults === customs) return;
					else return customs;
				};
				// look through customs for overwritten things
				while(key = ckeys.shift()){
					item = defaults[ key ];
					// values missing from default, not already checked, are only on customs
					if(typeof item === 'undefined'){
						result[ key ] = customs[ key ];
						continue;
					};
					alt = customs[key];
					item = diffr( item, alt, {});
					if(typeof item !== 'undefined'){
						result[ key ] = item;
					};
				};
				item = key = ckeys = 0;
				if(!/\[]|{}/.test(JSON.stringify(result))) return result;
			};

			return diffr(defaults, customs, diffs);
		}