How to properly export a module/library?

Question

Node.js

Hello!
I want to make an application on Electron. Here is the project structure:

The application calls the index.html file. To which backup.js is connected...
But in dev tools I get the following:

Uncaught ReferenceError: require is not defined at backup.js:1

And in this line: This library is vital for my script to cook under the hood of my application. How to make it work? How to load this library correctly?
var win = require("win-service");