Is it possible to use 2 factory functions to populate 1 instance?

Question

Using a single factory function to populate an instance is straightforward. In the example below I use the factory function aircraftFactory() to create a new instance called supermarine . However I'm not sure how to structure this so that both aircraftFactory() and engines() could be used together to create supermarine .

 "use strict" function aircraftFactory(x) { return { manufacturer: x.manufacturer, factory: x.factory } } function engines(x) { return { numberOfEngines: x.numberOfEngines, costPerEngine: x.costPerEngine } } let supermarine = aircraftFactory({manufacturer: 'Supermarine', factory: 'Southampton'}); document.querySelector('.output').textContent = supermarine.manufacturer; 

 <div class='output'></div> 

I tried chaining them together like this but it threw an error.

Uncaught TypeError: aircraftFactory(...).engines is not a function

 let supermarine = aircraftFactory({manufacturer: 'Supermarine', factory: 'Southampton'}).engines({numberOfEngines: 1, costPerEngine: 35000}); 

I know there must be a pattern but I can't find an example or figure it out. Thanks for any help!

Answer 1

I think I have a suggestion for you:

function engines(x) {
    return {
        numberOfEngines: x.numberOfEngines,
        costPerEngine: x.costPerEngine
    }
}

If you pass an engine:

function aircraftFactory(x, engine) {
    let aircraft = {
        manufacturer: x.manufacturer,
        factory: x.factory
    };

    if (engine) {
      aircraft.numberOfEngines = engine.numberOfEngines;
      aircraft.costPerEngine = engine.costPerEngine;
    }

    return aircraft;
}

You could create an instance like this:

let aircraft = aicraftFactory(x, engineFactory(y));

But if you want to create the properties without knowing the names:

function aircraftFactory(x, extended) {
    let aircraft = {
        manufacturer: x.manufacturer,
        factory: x.factory
    };

    if (engine) {
        for (let key in extended) {
            aircraft[key] = extended[key];
        }
    }

    return aircraft;
}

Answer 2

To extend engines to aircraftFactory you need to use prototype

Prototypes extends/inherit your properties and methods.

Try this

"use strict"

function aircraftFactory(x) {
  this.manufacturer = x.manufacturer;
  this.factory = x.factory;
}

function engines(x) {
    return {
        numberOfEngines: x.numberOfEngines,
        costPerEngine: x.costPerEngine
    }
}

//This is where you extend engines
aircraftFactory.prototype.engines = engines;

//Create the instance of aircraftFactory
let supermarine = new aircraftFactory({manufacturer: 'Supermarine', factory: 'Southampton'}).engines({numberOfEngines: 1, costPerEngine: 35000});