面试官：怎么准确判断JS的数据类型？

1、console.log(typeof 1) // number
2、console.log(typeof 'str') // string
3、console.log(typeof true) // boolean
4、console.log(typeof undefined) // undefined
5、console.log(typeof {}) // object
6、console.log(typeof []) // object
7、console.log(typeof null) // object
8、console.log(typeof function() {}) // object
9、console.log(type typeof new RegExp()) // object

console.log({} instanceof Object) // true
console.log([] instanceof Array) // true
console.log(new Date() instanceof Date) // true
console.log(1 instanceof Number) // false
console.log('str' instanceof String) // false
console.log(null instanceof Object) // false

function Father(){}
function Sun(){}
Sun.prototype = new Father();
Sun.prototype.constructor = Sun;
let sun = new Sun();
sun.constructor === Sun    // true
sun.constructor === Sun  // false
sun.constructor === Object 

 Object.prototype.toString.call(true) //[object Boolean]
 Object.prototype.toString.call(1) //"[object Number]"
 Object.prototype.toString.call('str') //"[object String]"
 Object.prototype.toString.call({}) //"[object Object]"
 Object.prototype.toString.call(function () {}) //"[object Function]"
 Object.prototype.toString.call(Undefined) //"[object Undefined]"
 Object.prototype.toString.call(Null) //"[object Null]"
 Object.prototype.toString.call(new RegExp()) //"[object RegExp]"
  等等