get the accurate type of certain data by native JavaScript

typeof.js

var _create = Object.create,
	_slice = Array.prototype.slice,
	_toString = Object.prototype.toString,
	_hasOwn = Object.prototype.hasOwnProperty;
/**
 * [getTypeOf Get the data type of some data]
 * @param  {any type} arg [the data to get type]
 * @return { string }     [the string to describe the data type]
 *
 * usage: 
 * getTypeOf(1) === 'number'
 * getTypeOf(null) === 'null'
 * getTypeOf(NaN) === 'NaN'
 * getTypeOf([1,2,3]) === 'array'
 * getTypeOf(new Number(1)) === 'object number'
 * getTypeOf(new Error('error')) === 'error'
 * getTypeOf(new function Foo(){}) === 'foo'
 * getTypeOf(window) === 'window'
 * getTypeOf(document) === 'htmldocument'
 * getTypeOf(document.createTextNode('hello')) === 'text'
 */
function getTypeOf(arg) {
	var t1, t2;
	if((t1 = typeof arg) === 'object') {
		t2 = _toString.call(arg).slice(8, -1).toLowerCase();
		switch(t2) {
			case 'number':
			case 'string':
			case 'boolean':
			// 'object number','object string','object boolean'
				return [t1, t2].join(' ');
			case 'null':
			case 'array':
			case 'date':
			case 'regexp':
				return t2;
			default:
			// 'person'
				return arg.constructor.toString().match(/function\s*([^\(\s]*)/)[1].toLowerCase();
		}
	} else if (t1 === 'function') {
		return t1;
	} else {
		switch (t1) {
			case 'undefined':
			case 'boolean':
			case 'string':
				return t1;
			case 'number':
				if(isNaN(arg)) return 'NaN';
				if(!isFinite(arg)) return 'Infinity';
				return t1;
			default:
				console.log('Error: type - something get wrong.');
		}
	}
}