Javascript：如果该构造函数已在另一个对象的原型上定义，则如何追加到该构造函数的原型

Question

If I wanted an API to allow for aggregation-like inheritance using closures and the module pattern, I've come up with something like this:

function Vehicle(category) {
    this.category = category;
    return {
        Car: this.Car
    };
};

Vehicle.prototype.Car = function(type) {
    this.wheels = [];
    this.type = type;
    return {
        type: this.type,
        wheels: this.wheels,
        addWheel: this.addWheel,
    };
};

Vehicle.prototype.Car.prototype.addWheel = function() {
    this.wheels.push('a wheel');
};

roadCars = new Vehicle('Road Cars');
roadCars.honda = new roadCars.Car('Honda');
roadCars.honda.addWheel();

console.log(roadCars.honda.wheels); // [ 'a wheel' ]

This provides the API that I want when dealing with creating sub objects. However this line:

Vehicle.prototype.Car.prototype.addWheel = function() {
    this.wheels.push('a wheel');
};

seems like it should be written differently. Ideally I would want to be able to append to the sub-constructor's prototype without specifying the entire prototype chain.

Also, are there any better ways to achieve the same API?

Answer 1

why not creating new function Car

function Vehicle(category) {
    this.category = category;
    return {
        Car: this.Car
    };
};

function Car(type) {
    this.wheels = [];
    this.type = type;
    return {
        type: this.type,
        wheels: this.wheels,
        addWheel: this.addWheel,
    };
};

Car.prototype.addWheel = function() {
    this.wheels.push('a wheel');
};

Vehicle.prototype.Car = Car

roadCars = new Vehicle('Road Cars');
roadCars.honda = new roadCars.Car('Honda');
roadCars.honda.addWheel();

console.log(roadCars.honda.wheels); // [ 'a wheel' ]