调用基类函数 - JavaScript中的类继承

Question

请查看以下示例:

MyBaseClass = function(a) {
     this.a = a;
};

$.extend(MyBaseClass.prototype, {
    init: function() {
        console.log('I am initializing the base class');
    }
});

MyChildClass = $.extend(MyBaseClass, {
    init: function() {
        MyBaseClass.prototype.init();
        console.log('I am initializing the child class');
    }
});

var = new MyChildClass();
var.init();

它应该输出'我正在初始化基类'和'我正在初始化子类'.

我需要能够继承MyBaseClass类,但仍然能够在新的init()方法的开头调用他的init()方法.

我怎么做？

Answer 1

jQuery的扩展不构建继承,而是"将两个或多个对象的内容合并到第一个对象中".

使用基于原型的继承来实现继承并显式调用"超级"方法:

MyBaseClass = function(a) {
     this.a = a;
};
MyBaseClass.prototype.init = function() {
    console.log('I am initializing the base class');
};

MyChildClass = function(a) {
  this.a = a;
}
MyChildClass.prototype = Object.create(MyBaseClass.prototype); // makes MyChildClass "inherit" of MyBaseClass
MyChildClass.prototype.init = function() {
    MyBaseClass.prototype.init.call(this); // calls super init function
    console.log('I am initializing the child class');
};

var child= new MyChildClass();
child.init();

输出:

I am initializing the base class
I am initializing the child class