[austincheney]

Forms cannot be nested. That is an html violation. That is because all submit events fire on all nodes contained by a form on submission even if the page does not go anywhere. Forms also require an action attribute that contains a submission address, which requests a new page on submission.

[yosamino]

Not the same thing as nesting forms, but when faced with similar challenges I found the <input form="form-id" /> attribute[0] is a good solution.

The trade-off is that you have to specify it almost every single time, but it lets you group form elements that for UX purposes belong together, but for other reasons need different forms.

[0] https://developer.mozilla.org/en-US/docs/Web/HTML/Element/in...

[Varriount]

What circumstances call for nesting form elements,?

[testudovictoria]

If a dev finds a form to be nested, it's usually because something was tacked on as an afterthought. I'm speaking from experience.

I had a project that had applications associated with it. Forms are the natural way to express this. There were some disclosures associated with the application, and there was a modal associated with emailing the disclosures. I needed to add some front end validations to this modal.

No matter what I tried, I could not get these validations to trigger correctly. I spent an entire work day on trying to get a library to work with this modal. It wouldn't work, because changing the modal's div to a form tag would cause errors or unexpected behavior due to the nested form tags.

TL;DR: Nothing requires it. Devs might not understand the implications.

[austincheney]

None. There is no good reason to do this. It doesn't stop people from doing it.

[MaurizioPz]

working with web forms https://docs.microsoft.com/en-us/aspnet/web-forms/ (Oh the nightmares!)