Some type util methods.

type.extras.js

/**
 * Type Extras, version 1.0
 * Copyright (c) 2012, marlun78
 * MIT License, https://gist.github.com/marlun78/bd0800cf5e8053ba9f83
 */
(function (ns) {

    // Returns an given element's internal [[Class]] property as a lower-case string
    var _toString = Object.prototype.toString,
        typeOf = function (object) {
            return _toString.call(object).slice(8, -1).toLowerCase();
        };

    ns.isArguments = function (object) {
        return typeOf(object) === 'arguments';
    };

    ns.isArray = function (object) {
        return typeOf(object) === 'array';
    };

    ns.isFunction = function (object) {
        return typeOf(object) === 'function';
    };

    ns.isNull = function (object) {
        return typeOf(object) === 'null';
    };

    // Note! isNumber(NaN) will return true!
    // Do detect if the object is a NaN value, 
    // use isNaN(object) or object !== object (Yes, NaN !== NaN is true!)
    ns.isNumber = function (object) {
        return typeOf(object) === 'number';
    };

    ns.isObject = function (object) {
        return typeOf(object) === 'object';
    };

    ns.isString = function (object) {
        return typeOf(object) === 'string';
    };

    ns.isUndefined = function (object) {
        return typeOf(object) === 'undefined';
    };

    // Expose the typeOf() method
    ns.typeOf = typeOf;

}(window.APP));