js面试题-----面向对象类

代码如下

<script type="text/javascript">
      /**
       * 类的声明
       */
      var Animal = function () {
          this.name = 'Animal';
      };

      /**
       * es6中class的声明
       */
      class Animal2 {
          constructor () {
              this.name = 'Animal2';
          }
      }

      /**
       * 实例化
       */
      console.log(new Animal(), new Animal2());

      /**
       * 借助构造函数实现继承
       */
      function Parent1 () {
          this.name = 'parent1';
      }
      Parent1.prototype.say = function () {

      };
      function Child1 () {
          Parent1.call(this);
          this.type = 'child1';
      }
      console.log(new Child1(), new Child1().say());

      /**
       * 借助原型链实现继承
       */
      function Parent2 () {
          this.name = 'parent2';
          this.play = [1, 2, 3];
      }
      function Child2 () {
          this.type = 'child2';
      }
      Child2.prototype = new Parent2();

      var s1 = new Child2();
      var s2 = new Child2();
      console.log(s1.play, s2.play);
      s1.play.push(4);

      /**
       * 组合方式
       */
      function Parent3 () {
          this.name = 'parent3';
          this.play = [1, 2, 3];
      }
      function Child3 () {
          Parent3.call(this);
          this.type = 'child3';
      }
      Child3.prototype = new Parent3();
      var s3 = new Child3();
      var s4 = new Child3();
      s3.play.push(4);
      console.log(s3.play, s4.play);

      /**
       * 组合继承的优化1
       * @type {String}
       */
      function Parent4 () {
          this.name = 'parent4';
          this.play = [1, 2, 3];
      }
      function Child4 () {
          Parent4.call(this);
          this.type = 'child4';
      }
      Child4.prototype = Parent4.prototype;
      var s5 = new Child4();
      var s6 = new Child4();
      console.log(s5, s6);

      console.log(s5 instanceof Child4, s5 instanceof Parent4);
      console.log(s5.constructor);

      /**
       * 组合继承的优化2
       */
      function Parent5 () {
          this.name = 'parent5';
          this.play = [1, 2, 3];
      }
      function Child5 () {
          Parent5.call(this);
          this.type = 'child5';
      }
      Child5.prototype = Object.create(Parent5.prototype);

    </script>