SOURCE

const N = 2
const S = '2'
const B = true
//强制类型转化——N
// console.log(typeof N)
console.log(typeof N.toString())
console.log(typeof String(N))
console.log(typeof Boolean(N))
//强制类型转化——S
console.log(typeof S)
console.log(Number(S))
console.log(typeof Number(S))
console.log(typeof Boolean(S))
//强制类型转化——B
console.log(typeof B)
console.log(Number(B))
console.log(typeof Number(B))
console.log(typeof B.toString())
console.log(typeof String(B))
//null,undefined
console.log(Number(null))
console.log(Number(undefined))
console.log(typeof Number(null))
console.log(typeof Number(undefined))
console.log(Boolean(null))
console.log(Boolean(undefined))
console.log(String(null))
console.log(String(undefined))
console.log(typeof String(null))
console.log(typeof String(undefined))