czsdfhj / study

keep study

<title>面向对象</title> <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>