var a = '123';
console.log(typeof(a));
/**
 * 
    1.typeOf()
    2.instanceof:
    格式：A instanceof B 判断A是否是B的实例对象  true/false 由构造函数类型去判断数据类型
    3.Object.prototype.toString.call()
    4.constructor
 */
let arr = new Date();
let fn1 = () => {
    console.log("函數")
}
console.log(fn1 instanceof Function);
console.log(Object.prototype.toString.call(true))
let arr1 = [];
console.log(arr1.constructor == Object)
let num = '111'
console.log(num.constructor)