javascript中的封裝多態和繼承

封裝Encapsulation

如下代碼,這就算是封裝了

(function (windows, undefined) {

    var i = 0;//相對外部環境來說,這裡的i就算是封裝了

})(window, undefined);

繼承Inheritance

(function (windows, undefined) {

    //父類

    function Person() { }

    Person.prototype.name = "name in Person";

    //子類

    function Student() { }

    Student.prototype = new Person();           //修複原型

    Student.prototype.constructor = Student;    //構造函數

    Student.prototype.supr = Person.prototype;  //父類

    //創建子類實例

    var stu = new Student();

    Student.prototype.age = 28;

    Student.prototype.name = "name in Student instance";

    //列印子類成員及父類成員

    alert(stu.name); //name in Student instance

    alert(stu.supr.name); //name in Person

    alert(stu.age); //28

})(window, undefined);

多態Polymorphism

有了繼承,多態就好辦了

//這就是繼承了

(function (windows, undefined) {

    //父類

    function Person() { }

    Person.prototype.name = "name in Person";

    Person.prototype.learning = function () {

        alert("learning in Person")

    }

    //子類

    function Student() { }

    Student.prototype = new Person();           //修複原型

    Student.prototype.constructor = Student;    //構造函數

    Student.prototype.supr = Person.prototype;  //父類

    Student.prototype.learning = function () {

        alert("learning in Student");

    }

    //工人

    function Worker() { }

    Worker.prototype = new Person();           //修複原型

    Worker.prototype.constructor = Worker;    //構造函數

    Worker.prototype.supr = Person.prototype;  //父類

    Worker.prototype.learning = function () {

        alert("learning in Worker");

    }

    //工廠

    var personFactory = function (type) {

        switch (type) {

            case "Worker":

                return new Worker();

                break;

            case "Student":

                return new Student();

                break;

        }

        return new Person();

    }

    //客戶端

    var person = personFactory("Student");

    person.learning(); //learning in Student

    person = personFactory("Worker");

    person.learning(); //learning in Worker

})(window, undefined);

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