Changes to process module in one file don’t show up in another

The process module in NodeJS doesn’t seem to be global. In other words, the changes I make to it in one module don’t show up in other modules.

I wrote a small piece of code to confirm demo my findings. Here is the code:

server.js

import app from "./app.js";
 
process.on("uncaughtException", (err) => {
  console.log("UNCAUGHT EXCEPTION: shutting down ...");
  console.log(err.name, err.message);
  process.exit(1);
});
 
// Server
const port = process.env.PORT || 3000;
const server = app.listen(port, () => {
  console.log(`App running on port ${port}...`);
});

app.js

import express from 'express'
 
const app = express();
 
console.log(y)    
 
export default app;

When I run the code with node server.js, I get a following error:

file:///tmp/node-test/app.js:5
console.log(y);
            ^
 
ReferenceError: y is not defined
    at file:///tmp/node-test/app.js:5:13
    at ModuleJob.run (node:internal/modules/esm/module_job:193:25)

However when I move a line console.log(y) into server.js I get an error that looks like this:

UNCAUGHT EXCEPTION: shutting down ...
ReferenceError y is not defined

Which is what I expected to see when console.log(y) was in app.js.

It looks like changes I made in server.js with respect to process don’t show up in app.js. I tried to find an answer online, but came up empty. My search foo wasn’t good enough.

Does anyone know what’s going on and how do I fix it? Because of coding standards I cannot use require, I must use import