Warn when formAction is used without a form

[sophiebits]

No description provided.

[react-sizebot]

Comparing: fda1f0b...fed72e3

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	164.19 kB	164.19 kB	=	51.78 kB	51.78 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	171.55 kB	171.55 kB	=	53.98 kB	53.98 kB
facebook-www/ReactDOM-prod.classic.js	=	570.13 kB	570.13 kB	=	100.62 kB	100.62 kB
facebook-www/ReactDOM-prod.modern.js	=	553.87 kB	553.87 kB	=	97.80 kB	97.80 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against fed72e3

[sebmarkbage]

This isn't limited to formActions as functions but applies to all formAction non-null values on input/button. Since we also track nesting of DOM nodes we should be able to warn about this earlier instead of waiting for the action to be invoked.

How about we do the warning in the render phase by checking DOM nesting instead?

The risk is that we don't know if you're rendering the React root into a form but we can either just assume that you're not and warn. Seems like such an edge case or check at the root.

[sophiebits]

Yeah I figured I'd not add warnings for existing code and I was thinking the non-React form container might happen. But you're right it's probably rare so maybe we just should.

[sebmarkbage]

Even if we add the warning for non-functions for existing code behind a flag for later, it seems nicer to get the warning earlier rather than later. Since this is something that seems like you could accidentally do even during a simple refactor.

Another interesting thing is that we don't warn for nested forms in the case where you render into one so you might be tempted to add one as a wrapper when you get this warning which wouldn't be quite correct. Although it probably works as long as it's not SSR.

[sophiebits]

Weirdly we would catch invalid form nesting if the container is a form, but not if the container is inside a form. I left that logic as-is for now. I suppose since you can reparent containers that makes sense in some sense. For SSR into a form ancestor you wouldn't get the warning but you would get the hydration error, which seems fine since it should be rare.

With diffInCommitPhase it looks like the bindings currently don't have access to hostContext anytime during updates.