ES5

var employee1 = {
  name: "kerwin",
  age: 100,
};

var employee2 = {
  name: "tiechui",
  age: 100,
};

function Employee(name, age) {
  this.name = name;
  this.age = age;
}

Employee.prototype.say = function () {
  console.log(this.name + "_" + this.age);
};

var employee1 = new Employee("kerwin", 100);
var employee2 = new Employee("tiechui", 10);

ES6

class Employee {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
  say() {
    console.log(this.name + "_" + this.age);
  }
}

var employee1 = new Employee("kerwin", 100);
console.log(employee1);
employee1.sqy();

// 在class中， say方法是挂载到原型上的。