js面向对象基础总结

 

 js中如何定义一个类？

定义的function就是一个构造方法也就是说是定义了一个类；用这个方法可以new新对象出来。

function Person(name, age){

  this.name = name;

  this.age = age;

  this.showInfo = function(){

    alert(this.name + this.age + "岁");

  }

}

Person p1 = new Person('小明', 17);

 类的继承

我们把具有相同属性特征的类放到一个父类里，通过继承子类同样拥有父类的属性和特征。其中继承方法有对象冒充和原型链继承。

对象冒充：

function Rect(width, height){

    this.width = width;

    this.height = height;

    this.area = function(){return this.width*this.height;};

}

 

function MyRect(width, height, name){

//    this.newMethod = Rect;

//    this.newMethod(width,height);

//    delete this.newMethod;

    Rect.call(this,width,height);// Rect.apply(this, arguments);

    this.name = name;

    this.show = function(){

        alert(this.name+" with area:"+this.area());

    }

}

原型链（prototype chaining）:

function Rect(){

}

Rect.prototype = {

        width:10,

        height : 10,

        area : function(){return this.width*this.height;}

};

 

function MyRect(name){

    this.name = name;

    this.show = function(){

        alert(this.name + " with area:" + this.area());

    }

}

MyRect.prototype = new Rect();