Generate randomNumber in server every X seconds

Background

I am making a Node.js app that generates a random number every 6 seconds, and makes it available via an API.

To keep the number generation logic out of the API file, I encapsulated in a function called numberGen, in another file.

api.js

const express = require("express");
const numberFactory = require("../numberGen.js");

module.exports = (function() {
    let interval = 6, min = 0, max = 100;

    const api = express.Router();
    const numberGen = numberFactory({
        interval, min, max
    });
    numberGen.run();

    api.get("/Numbers/", (req, res) => {
        res.json({ random: numberGen.currNum});       
    });

    return api;
})();

numberGen.js

"use strict";

module.exports = function(args) {
    let {
        interval,
        min,
        max
    } = args;

    let currNumber = genRandom(min, max);

    function run() {
        setTimeout(() => {
            currNumber = genRandom(min, max);
            run();
        }, interval);
    }

    function genRandom(min, max){
        return Math.floor(Math.random() * max) + min;
    }

    return {
        interval, currNumber,
        run
    };
};

Ideally, a client make a request at 0 seconds, would get number X, and making the same request 6 seconds after, would get a number Y, as the server generates a new random number every 6 seconds.

Problem

The problem here is that the client always gets the same number, no matter what.

Tentatives

At first I thought this was happening because numberGen is returning an object that never changes. To fix it, I tried passing a number from the api.js to the generator to update, but it didn't work either as the client always gets an empty object, because serverNum === undefined;

numberGen.js

"use strict";

module.exports = function(args) {
    let {
        interval,
        min,
        max,
        serverNum
    } = args;

    serverNum = genRandom(min, max);

    function run() {
        setTimeout(() => {
            serverNum= genRandom(min, max);
            run();
        }, interval);
    }

    function genRandom(min, max){
        return Math.floor(Math.random() * max) + min;
    }

    return {
        interval,
        run
    };
};

api.js

const express = require("express");
const numberFactory = require("../numberGen.js");

module.exports = (function() {
    let interval = 6, min = 0, max = 100, serverNum;

    const api = express.Router();
    const numberGen = numberFactory({
        interval, min, max, serverNum
    });
    numberGen.run();

    api.get("/Numbers/", (req, res) => {
        res.json({ random: serverNum});       
    });

    return api;
})();

Question

Having in mind I want to keep this logic separated from the api.js file, how can I fix my code?

via Flame_Phoenix