reduce-until & iteration-context & generator-to-array & fibonacci-generator

fibonacci-generator.js

export default function* fibonacciGenerator() {

    let prev = 1;
    let cur = 1;

    yield prev;

    while(true) {
        yield cur;
        [prev, cur] = [cur, prev + cur];
    }
}

generator-to-array.js

import * as iterationContext from "./iteration-context";
import reduceUntil from "./reduce-until";

export default function generatorToArray(gen, limit) {

    let iteContext = iterationContext.create(gen);

    return reduceUntil(
        Array.from({length: limit}),
        result => {
            iteContext = iterationContext.next(iteContext);
            result.push(iteContext.status.value);
            return result;
        },
        () => iteContext.status.done,
        []
    );
}

iteration-context.js

function create(generator) {

    const iterator = generator();

    return {
        iterator,
        status: undefined
    },
}

function next({iterator}) {

    return {
        iterator,
        status: iterator.next()
    };
}

export {
    create,
    next
};

main.js

import generatorToArray from "./generator-to-array";
import fibonacciGenerator from "./fibonacci-generator";

generatorToArray(fibonacciGenerator, 10); // [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]

reduce-until.js

export default function reduceUntil(arr, reduce, done, seed) {

    let result = seed;
    
    arr.some((elem, i) => {
        result = reduce(result, elem, i);
        return done(result);
    });

    return result;
}