Don't force directory structure on the user of your library

[funkjunky]

Why can't I simply provide the configurations in the code?

Don't assume you know how to architect code better than your clients.

[kevgathuku]

You can still provide the config to the Twitter object directly in your code
i.e.

let config = {
  consumerKey: "xxx",
  consumerSecret: "xxx",
  accessToken: "xxx",
  accessTokenSecret: "xxx",
  callBackUrl: "xxx"
};
let twitter = new Twitter(config);