Introduce callbacks to hide and show container.

[widoz]

Instead of using the "on" callbacks that for hide and show behavior,
allowing a callback will prevent the original functions to be called.

So for example, if I want to use slideUp/slideDown the animate effect will not be
performed because the show/hide will be performed before the animated functions.

[widoz]

If a valid feature I think will be possible to create new wrapper functions for show and hide.

Also, I used the "container" object as this for the function, may be pass as parameter is better?

[tkirda]

Thanks for this contribution, and apologies for the very long silence.

The project was dormant for several years and has just shipped v2.0, which is a ground-up TypeScript rewrite with a new build (esbuild), test runner (Vitest + jsdom), and CI pipeline. As a result this PR no longer applies cleanly against master, and the surrounding code it touches has changed enough that mechanically rebasing it wouldn't be safe.

I'm closing it as part of a triage pass on the long-stale PR backlog — not because the idea lacks merit. If this change is still valuable to you against 2.0, please open a fresh PR (or an issue first if you'd like to confirm direction); I'll review new submissions against the current codebase promptly.

Thanks again for taking the time.