@BKeyport Here’s a more detailed explanation for you and anyone who is curious.
The if (typeof module !== "undefined") {} line checks if there is a global variable named module. If there is, then we must be using a module system and we have to export config using module.exports = config;. If not, then we must be in the browser and config will already be available to any other modules.
In the browser, there is no concept of separate modules (a.k.a. files); script files are loaded in and simply concatenated one after the other. So if you load config.js and then another-file.js, the config variable (var config = { ... } ) will be available as a global variable in another-file.js. The module and require variables are not defined.
In more modern code with a module system, you have to export anything you want to use elsewhere, and import it in modules where you need it. Node.js uses module.exports = ... to export and ... = require("module-to-import") to import.