类型判断.md

类型判断

　　下面是我自己写的类型判断函数，适合 JavaScript 所有数据类型，有问题请及时指出。

function typeJudge(value){
    var basicType = {
	"undefined" : "基本类型：Undefined",
	"number"    : "基本类型：Number",
	"boolean"   : "基本类型：Boolean",
	"string"    : "基本类型：String",
	"symbol"    : "基本类型：Symbol",
    }
    var typeOfValue = typeof value;
    if(typeOfValue != "object" && typeOfValue != "function"){
	//若是基本类型,要注意有些浏览器对正则表达式使用typeof操作符会返回"function"
	return basicType[typeOfValue];
    }
    if(value == null){
	//若是null
	return "空对象或NULL类型";
    }
    var referenceType = {
	"[object String]"  : "基本包装类型：String",
	"[object Number]"  : "基本包装类型：Number",
	"[object Boolean]" : "基本包装类型：Boolean",
	"[object Date]"    : "引用类型：Date",
	"[object RegExp]"  : "引用类型：RegExp",
	"[object Array]"   : "引用类型：Array",
	"[object Function]": "引用类型：Function",
	"[object Window]"  : "内置对象：Global对象",
	"[object Math]"    : "内置对象：Math对象",
    }
    var protoClass = Object.prototype.toString.call(value);
    if(referenceType[protoClass] != undefined){
 	//引用类型中的一种（除自定义类型）
	return referenceType[protoClass];
    }
    //自定义类型
    return "自定义类：" + value.__proto__.constructor.name;
}

　　以下是一些测试代码：

//基本类型值检测
console.log(typeJudge(1));
console.log(typeJudge("a"));
console.log(typeJudge(true));
console.log(typeJudge(undefined));
var id = Symbol("id"); 
console.log(typeJudge(id));

//null
console.log(typeJudge(null));

//基本包装类型检测
var str = new String();
console.log(typeJudge(str));
var myBool = new Boolean();
console.log(typeJudge(myBool));
var myNumber = new Number();
console.log(typeJudge(myNumber));

//Date,RegExp,Function类型检测
var date = new Date();
console.log(typeJudge(date));
var reg = /at/g;
console.log(typeJudge(reg));
console.log(typeJudge(typeJudge));

//window,Math内置对象检测
console.log(typeJudge(window));
console.log(typeJudge(Math));

//自定义类型检测
function Person(name,age){
    this.name = name;
    this.age = age;
}
var person1 = new Person("Nicholas",29);
console.log(typeJudge(person1));

下面是 JavaScript 引用类型 的大致关系图：