原型和原型链

      
function Employee() {

}

const emp1 = new Employee();
      
class People {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
  say() {
    console.log("我的名字叫：", this.name);
  }
}
// const p1 = new People("黄大", 167);
// p1.say()

class Student extends People {
  constructor(name, age, clas) {
    super(name, age)
    this.clas = clas;
  }
  sayCalss() {
    console.log('我是' + this.clas + "年级的" + this.name);
  }
}

const s1 = new Student('野原新之助', 18, 6);

s1.say()
s1.sayCalss()
function onPrintClick() {
  s1.say()
  s1.sayCalss()
  console.log("Student.prototype.__proto__ === People.prototype：", Student.prototype.__proto__ === People.prototype);
}
// Student.prototype.__proto__ === People.prototype // true