缺点：前面两个问题解决，但父类构造函数会多执行一次

      function Parent3() {
        this.name = 'parent3'
        this.play = [1, 2, 3]
      }

      function Child3() {
        Parent3.call(this)
        this.type = 'child3'
      }
      Child3.prototype = new Parent3()
      
      const c31 = new Child3()
      const c32 = new Child3()
      c31.play.push(4)
      
      console.log(c31.play) // [1, 2, 3, 4]
      console.log(c32.play) // [1, 2, 3]