Adding a critical log level

[asasine]

We use loglevel for a website at school and are big fans of its plugins, especially sending to a remote server. We are attempting to configure our logger to raise incident emails/texts/notifications whenever very serious problems occur. Since we use error logs often enough, can a critical level be added, one step above error?

[pimterry]

For historical reasons, I'm afraid that's more difficult than it sounds. Internally, levels are stored numerically, with 0 being trace, up to 4 being error, and 5 being silent. If you set a level, every numerically lower level is silenced.

critical would have to be the new 5, bumping silent to 6, and this is a breaking change, because:

• We return these numbers from getLevel(), and people might well depend on 5 meaning 'logging is disabled'
• You can pass these numbers directly to setLevel(n), and people will very possibly expect setLevel(5) to disable logging

This isn't a great design for extensibility in levels, which is part of why I've avoided doing it until now, and I'm going to have to say no to this I'm afraid.

There are a few easy workarounds though. The obvious ones that jump to mind:

• Use a separate method to trigger your incident notifications, not your log messages
• Bump your non-critical errors to be warnings (if they're not critical, what's the difference?) and use error for this.
• Add a separate marker to your logged data ({ shouldLog: true }), and either detect that in your log output, or add a loglevel plugin that spots this case client-side and handles it differently.

Happy to chat about other solutions, but I think it's very unlikely I'm going to add this to the library, sorry.