is this not something that can go in a b/c/plugin?

It would require to load a file or have it inline for just one line of code on all pages then.

ah - ok

I just fear that this specific deprecation/removal will be like isSite/isAdmin

I don't think so. Perhaps we can do something when this gets accepted and load it as part of the core loading. But honestly I don't see such an urgency as it is on the JS side only.

Can we keep this? Keep this one line of code almost keep us nothing but removing it might make our users have trouble with their template overrides.

Can we keep this? Keep this one line of code almost cost us nothing but removing it might make our users have trouble with their template overrides.

This is Javascript and not PHP, so I doubt this code was ever used in a template override as we never had this in template files (as far as I know). If people added Javascript in template overrides, then they will be able to fix it. And if it is in a template override, then the site still leads, with a Javascript error, but no crash.

In the old days, we are using inline JS, so the JS code could be in template overrides. Yes, site still load, but the functionality of certain features could be broken. Developer can fix this, Yes, but it will cost site owner some fees. The point here is this is just one line of JS code, so there should be no problem if we keep it.

How long do you want to keep it?

I don't really know, maybe J8. I put it to meeting document for maintainers to decide.