type.js

type = (function(global) {
    var re = /\s([a-z|A-Z]+)/;
    
    return function(obj) {
        if (obj === global) {
            return 'global';
        }
        return Object.prototype.toString.call(obj).match(re)[1].toLowerCase();
    }
})(window);

type('123');
type(123);
type(window);