`a.js` is called before `b.js`. (There is some asynchronous stuff going one between the 2 calls). Here Visit is going to be undefined when required in `b.js`, no error thrown. If I call `require_public('models/Visit')` at position 1, it works fine. Even in `b.js`, Visit will be defined (probably because it's kept in memory once loaded).

a.js

modules.exports = function (app) {

    var requirejs = require("requirejs");
    var path = require("path");

    requirejs.config({
        baseUrl: path.join(app.config.paths.root, "public/js")
    });

    app.require_public = requirejs;

    // position 1
    
}

b.js

modules.exports = function (app) {

    // position 2
    var Visit = app.require_public('models/Visit');
    console.log("Visit", Visit);
}