JavaScript实现多态和继承的封装操作示例

封装Encapsulation

如下代码,这就算是封装了

(function (windows, undefined) {
  var i = 0;//相对外部环境来说,这里的i就算是封装了
})(window, undefined);

继承Inheritance

(function (windows, undefined) {
  //父类
  function Person() { }
  Person.prototype.name = "name in Person";
  //子类
  function Student() { }
  Student.prototype = new Person();      //修复原型
  Student.prototype.constructor = Student;  //构造函数
  Student.prototype.supr = Person.prototype; //父类
  //创建子类实例
  var stu = new Student();
  Student.prototype.age = 28;
  Student.prototype.name = "name in Student instance";
  //打印子类成员及父类成员
  console.log(stu.name); //name in Student instance
  console.log(stu.supr.name); //name in Person
  console.log(stu.age); //28
})(window, undefined);

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运行结果如下：

多态Polymorphism

有了继承,多态就好办了

//这就是继承了
(function (windows, undefined) {
  //父类
  function Person() { }
  Person.prototype.name = "name in Person";
  Person.prototype.learning = function () {
    console.log("learning in Person")
  }
  //子类
  function Student() { }
  Student.prototype = new Person();      //修复原型
  Student.prototype.constructor = Student;  //构造函数
  Student.prototype.supr = Person.prototype; //父类
  Student.prototype.learning = function () {
    console.log("learning in Student");
  }
  //工人
  function Worker() { }
  Worker.prototype = new Person();      //修复原型
  Worker.prototype.constructor = Worker;  //构造函数
  Worker.prototype.supr = Person.prototype; //父类
  Worker.prototype.learning = function () {
    console.log("learning in Worker");
  }
  //工厂
  var personFactory = function (type) {
    switch (type) {
      case "Worker":
        return new Worker();
        break;
      case "Student":
        return new Student();
        break;
    }
    return new Person();
  }
  //客户端
  var person = personFactory("Student");
  person.learning(); //learning in Student
  person = personFactory("Worker");
  person.learning(); //learning in Worker
})(window, undefined);

运行结果如下：