Functions for working with type detection.

typedetection.js

['Undefined', 'Null', 'Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp', 'Array', 'Object'].forEach( 
    function(name) { 
        var is = 'is' + name;
        if(!window.is)
            window[is] = function(obj) {
                return ({}).toString.call(obj) === '[object ' + name + ']';
    }; 
});

(function() {
    var a;
    function x() { return isArguments(arguments) };

    console.debug("isUndefined(a)                  : " + isUndefined(a));
    console.debug("isNull(null)                    : " + isNull(null));
    console.debug("isFunction(x)                   : " + isFunction(x));
    console.debug("isString('A string')            : " + isString("A string"));
    console.debug("isNumber(1)                     : " + isNumber(1));
    console.debug("isNumber(1.1)                   : " + isNumber(1.1));
    console.debug("isDate(new Date())              : " + isDate(new Date()));
    console.debug("isRegExp(/[a..z]/i)             : " + isRegExp(/[a..z]/i));
    console.debug("isArray([1,2,3])                : " + isArray([1,2,3]));
    console.debug("isObject({a:1,b:2,c:3})         : " + isObject({a:1,b:2,c:3}));
    console.debug("isObject(new Object())          : " + isObject(new Object()));
    console.debug("isArguments(arguments)          : " + isArguments(arguments));
    console.debug("isArguments x(1, 2, {a:4, b:5}) : " + x(1, 2, {a:4, b:5}));
    console.debug("isArguments x({a:4, b:5})       : " + x({a:4, b:5}));
}());