fantasy/painting/factory.js

import Rectangle from "./rectangle.js";
import Circle from "./circle.js";
import Triangle from "./triangle.js";

const options = {
    rectangle: Rectangle,
    circle   : Circle,
    triangle : Triangle
};

let collection = [
    Circle, Rectangle, Triangle
];

export default {
    createRandomShape: function() {
        let Shape = collection[Math.floor(Math.random() * collection.length)];

        return Shape.fromOptions(Shape.randomOptions());
    },
    setCollection(obj) {
        collection = [];
        let keys = Object.keys(obj);
        for (let i = 0; i < keys.length; ++i) {
            let key = keys[i];
            if (obj[key]) {
                collection.push(options[key]);
            }
        }
    }
};