Does 'debug' cache the DEBUG environment variable somewhere? Getting no output after changing namespace and DEBUG env var.

[KerimG]

I am using 'debug' with TypeScript in an Electron project like so:

import debug from 'debug';
const log = debug('foo');

export default async function myFunction(name: string) {
  log('calling myFunction');
  ...
  log('successfully returning myFunction');
  return someVariable;
}

in my shell (zsh) I set the DEBUG env var like so export DEBUG=foo and then started running my application. Everything worked fine. Eventually, I changed the namespace from foo to bar and now no matter what I do, I cannot get any output. I tried resetting DEBUG, I restarted my shell and set the environment variable again with export DEBUG=bar, I tried using the [cross-env]{https://www.npmjs.com/package/cross-env} to set it like so:

"scripts": {
    "start": "tsc && cross-env DEBUG=bar NODE_ENV=development electron-forge start",
    ...
}

but nothing ever shows up. I tried

import debug from 'debug';
const log = debug('bar');

console.log("DEBUG", process.env.DEBUG);

export default async function myFunction(name: string) {
  log('calling myFunction');
  ...
  log('successfully returning myFunction');
  return someVariable;
}

and the console.log output is indeed: DEBUG bar.

The only way I can get it to work now is by doing:

import debug from 'debug';
const log = debug('bar');
log.enabled = true;

The moment I change const log = debug('bar'); back to const log = debug('foo'); , I get output messages for the foo namespace no matter what's in the DEBUG env var.

Any idea what might be happening here?

[robigan]

Having a similar issue here, but just to help you, maybe try running export on it's own to print a debug output of all environment variables that will be exported to children processes

[Qix-]

No idea, this seems like an environment issue to be honest. DEBUG is checked once at the first import of debug and cached.

[algernon]

I've been bitten by this the other day too. Turns out, DEBUG is cached in LocalStorage, and in subsequent runs, LocalStorage will override the environment. You can do localStorage.debug = null in a dev console to reset it.

[Qix-]

@algernon that's a detail of the browser version. I believe OP is using the node side of things.

[abenhamdine]

Same issue with Remix today, process.env shows the correct expected DEBUG string, but debugnever outputs anything. Very weird.

[GodBleak]

Are/were you using regex in your code somewhere? possibly passing it into debug? I think this issue was introduced with toNamespace() in 4.1.0

When I had DEBUG = *, I saw express was able to debug fine. I noticed that they're using debug 2.6.9, so I went through the versions and found that debug works as expected until 4.1.0. Seeing that toNamespace converts regex into a namespace and realizing I was potentially passing regex into debug, I remembered Javascript's regex is weird. commenting out my regex returned the output in 4.3.4.

However, at that point, the universe decided I was done, as uncommenting it did not reintroduce the issue and no matter what I do now I can't reproduce it again, I've rolled everything back to exactly as it was when I had the problem and it's just gone 🤷