前言：ECMAScript有5中简单数据类型(也称为基本数据类型)：Undefined，Null，Boolean，Number和String。还有一种复杂数据类型：object 。而用typeof操作符去分辨这些数据类型是件很让人奔溃的事情。
一、typeof检测数据
var obj = {};
var str = 'string';
var num = 123;
var bool = true;
var arr = [];
var reg = /a-z/;
var fn = function(){};
var obj_null = null;
var undf = undefined;
console.log(typeof obj); //object
console.log(typeof str); //string
console.log(typeof num); //number
console.log(typeof bool); //boolean
console.log(typeof arr); //object
console.log(typeof reg); //object
console.log(typeof fn); //function
console.log(typeof obj_null); //object
console.log(typeof obj_undf); //undefined
这时，除了对象输出的是'object'外，还有数组输出的也是'object'，正则reg输出的也是'object'，null输出的也是'object'。
二、检测new创建数据类型
var obj2 = new Object();
var obj_str = new String('string');
var obj_num = new Number();
var obj_bool = new Boolean();
var obj_arr = new Array();
var obj_reg = new RegExp();
var obj_fn = new Function();
var obj_date = new Date();
console.log(typeof obj2); //object
console.log(typeof obj_str); //object
console.log(typeof obj_num); //object
console.log(typeof obj_bool); //object
console.log(typeof obj_arr); //object
console.log(typeof obj_reg); //object
console.log(typeof obj_fn); //function
console.log(typeof obj_date); //object
这时，除了obj_fn，即通过new Funciton()创建的输出的是'function'外，其他输出的全是'object'。这令人很头疼。
三、封装可以分辨所有数据类型的方法
var typeName = {
'[object Function]': 'function',
'[object Boolean]': 'boolean',
'[object Number]': 'number',
'[object String]': 'string',
'[object Object]': 'object',
'[object RegExp]': 'regExp',
'[object Array]': 'array',
'[object Error]': 'error',
'[object Date]' : 'date'
};
var toStringFn = Object.prototype.toString; //获取到对象的toString方法
//通过call 引用toString方法。
function checkType(obj){
if( obj == null ){
return String( obj ); //js自带的的String方法，用于检测null和undefined
}
//safari5及之前版本，Chrome7, typeof RegExp返回的是function
return typeof obj ==='object' || typeof obj === "function" ?
typeName[toStringFn.call(obj)]:typeof obj;
}
用checkType检测数据类型
var obj = {};
var str = 'string';
var num = 123;
var bool = true;
var arr = [];
var reg = /a-z/;
var fn = function(){};
var obj_null = null;
var undf = undefined;
var obj2 = new Object();
var obj_str = new String('string');
var obj_num = new Number();
var obj_bool = new Boolean();
var obj_arr = new Array();
var obj_reg = new RegExp();
var obj_fn = new Function();
var obj_date = new Date();
console.log(checkType(obj)); //object
console.log(checkType(str)); //string
console.log(checkType(num)); //number
console.log(checkType(bool)); //boolean
console.log(checkType(arr)); //array
console.log(checkType(reg)); //regExp
console.log(checkType(fn)); //function
console.log(checkType(obj_null)); //null
console.log(checkType(obj_undf)); //undefined
console.log('-----------------------分界线');
console.log(checkType(obj2)); //object
console.log(checkType(obj_str)); //string
console.log(checkType(obj_num)); //number
console.log(checkType(obj_bool)); //boolean
console.log(checkType(obj_arr)); //array
console.log(checkType(obj_reg)); //regExp
console.log(checkType(obj_fn)); //function
console.log(checkType(obj_date)); //date
这时就可以清晰的检测所有的数据类型了。
相关链接：