type.js

(function (toString) {

	return {
		isFunction  : _partial(_partial),
		isArray     : _partial([]),
		isObject    : _partial({}),
		isString    : _partial(""),
		isRegExp    : _partial(/./),
		isNumber    : _partial(0),
		isArguments : _partial(arguments)
	};

	function _partial (obj1){
		var str = toString.call(obj1);
		return function (obj2){
			return str === toString.call(obj2);
		};
	}

}(Object.prototype.toString));