如何实现类？

方法一：使用原型

function Person(name, age) {
  this.name = name
  this.age = age
}
Person.prototype.sayHi = function() {
  console.log(`hi, my name is ${this.name}, I'm ${this.age} year's old.`)
}
const xiaoming = new Person('小明', 16)
xiaoming.sayHi()

方法二: 使用 class

class Person{
  constructor(name, age){
    this.name = name
    this.age = age
  }
  sayHi(){
    console.log(`hi, my name is ${this.name}, I'm ${this.age} year's old.`)
  }
}
const xiaoming = new Person('小明', 16)
xiaoming.sayHi()