第37题 实现ES6的class

js 的完美继承是寄生组合继承

    // Parent
    function Parent(name) {
      this.name = name
    }
    Parent.prototype.sayName = function () {
      console.log(this.name)
    };
    
    
    // Child
    function Child(age, name) {
      Parent.call(this, name)
      this.age = age
    }
    Child.prototype = Object.create(Parent.prototype)  // 原型拷贝
    Child.prototype.constructor = Child // 重置子类constructor，否则子类实例constructor将指向Parent
    
    Child.prototype.sayAge = function () {
      console.log(this.age)
    }
    
    // 测试
    const child = new Child(20, 'poetry')
    child.sayName()
    child.sayAge()