70-继承方式四-终极方案

终极方案

• 在子类的构造函数中通过 call 借助父类的构造函数

• 将子类的原型对象修改为父类的实例对象

      function Person(myName, myAge) {
          // let per = new Object();
          // let this = per;
          // this = stu;
          this.name = myName; // stu.name = myName;
          this.age = myAge;   // stu.age = myAge;
  
          // this.say = function () {    // stu.say = function () {}
          //     console.log(this.name, this.age);
          // }
          // return this;
      }
  
      Person.prototype.say = function () {
          console.log(this.name, this.age);
      }
  
      function Student(myName, myAge, myScore) {
          // let stu = new Object();
          // let this = stu;
          Person.call(this, myName, myAge); // Person.call(stu);
          this.score = myScore;
          this.study = function () {
              console.log("day day up");
          }
          // return this;
      }
  
      // 继承方式四就是把Student的原型对象改为Person实例对象
      Student.prototype = new Person();
      Student.prototype.constructor = Student;
      Student.prototype.run = function(){
          console.log("run");
      }
  
      let stu = new Student("ww", 19, 99);
      console.log(stu.score);  // 99
      stu.say();  // ww 19
      stu.study();  // day day up
  

  终极方案