一、 typeof
const a = 1
const b = 'b'
const c = new Object()
const d = /hello/
const e = function () {}
const f = undefined
const g = null
const h = []
const i = true
console.log(`a = 1 的类型为：${typeof a}`)
console.log(`b = 'b' 的类型为：${typeof b}`)
console.log(`c = new Object() 的类型为：${typeof c}`)
console.log(`d = /hello/ 的类型为：${typeof d}`)
console.log(`e = function () {} 的类型为：${typeof e}`)
console.log(`f = undefined 的类型为：${typeof f}`)
console.log(`g = null 的类型为：${typeof g}`)
console.log(`h = [] 的类型为：${typeof h}`)
console.log(`i = true 的类型为：${typeof i}`)
二、instanceof
instanceof主要用来判断引用类型属于哪一类- demo
const reg = new RegExp()
const array = []
const obj = new Object()
const fn = function () {}
console.log(`reg instanceof RegExp: ${reg instanceof RegExp}`)
console.log(`array instanceof Array: ${array instanceof Array}`)
console.log(`obj instanceof Object: ${obj instanceof Object}`)
console.log(`fn instanceof Function: ${fn instanceof Function}`)
三、Object.prototype.toString.call()
const a = 1
const b = 'b'
const c = new Object()
const d = /hello/
const e = function () {}
const f = undefined
const g = null
const h = []
const i = true
console.log(`a = 1 的类型为：${Object.prototype.toString.call(a)}`)
console.log(`b = 'b' 的类型为：${Object.prototype.toString.call(b)}`)
console.log(`c = new Object() 的类型为：${Object.prototype.toString.call(c)}`)
console.log(`d = /hello/ 的类型为：${Object.prototype.toString.call(d)}`)
console.log(`e = function () {} 的类型为：${Object.prototype.toString.call(e)}`)
console.log(`f = undefined 的类型为：${Object.prototype.toString.call(f)}`)
console.log(`g = null 的类型为：${Object.prototype.toString.call(g)}`)
console.log(`h = [] 的类型为：${Object.prototype.toString.call(h)}`)
console.log(`i = true 的类型为：${Object.prototype.toString.call(i)}`)
