How, who, implements the connection of modules?

Question

Node.js

Hello everyone, I was interested in such a question, maybe someone will throw off links to interesting articles or share their experience. That's the point. Let's say there is such a module - 1

Module - 1

exports.modul1= function () {
 console.log("New modul1")
}

Also module -2 which will call module 1

Unit 2

const m = require('./modul1');
m.modul1()
exports.modul2= function () {
 console.log("New modul2")
}

Well, 3, which will call module 1

Module -3

const m = require('./modul1');
m.modul1()
exports.modul3= function () {

 console.log("New modul3")
}

It turns out that two instances of the 1st module will be created in two different modules, so if there was a connection to MySQL in module 1, then 2 different connections would be created. If so, how can this be avoided. The only way that comes to my mind is with some such module

main

const m1 = require('./modul1');
    const m2 = require('./modul2');
    const m3 = require('./modul2');

    m2.modul2( m1 )
    m3.modul3( m1 )

Like declare everything in one file, call everything there and scatter variables, but isn't there really only such an option?

Answer 1

Everything is well described here)
https://medium.com/@lazlojuly/are-node-js-modules-...