How can I make use of functions from other js files in the index.js/main.js file?
Atom uses NodeJS (v7.9.0 as of writing this; can check with
atom -v). So you would use
require("path/to/file"). Here is a guide for it
Alternatively, using the
"use babel"; directive, you can use
import <name> from <module> syntax from ES6. More on this is best found in the docs