Improve ergonomics of action prop in next/form to align with HTML standards

[ChristianIvicevic]

Description

Earlier today, I tried out the new next/form component introduced in Next.js 15, and encountered a minor yet confusing detail regarding the action prop. In my use case, I wanted to append search parameters to the current route, which required me to set action="". This approach feels counterintuitive and doesn't align with the common HTML standard, where similar behavior can be achieved using <form method="GET"> or even just a basic <form> without an explicit action.

Observations

Upon reviewing the implementation in Next.js, I noticed the explicit usage of the NonNullable type in the source code:

next.js/packages/next/src/client/form.tsx

Lines 21 to 27 in 0ea736e

	/**
	* `action` can be either a `string` or a function.
	* - If `action` is a string, it will be interpreted as a path or URL to navigate to when the form is submitted.
	* The path will be prefetched when the form becomes visible.
	* - If `action` is a function, it will be called when the form is submitted. See the [React docs](https://react.dev/reference/react-dom/components/form#props) for more.
	*/
	action: NonNullable<HTMLFormProps['action']>

This choice makes the action prop mandatory, which is not equivalent to the default behavior of standard HTML forms. As a result, developers must explicitly set action="" to achieve the default behavior, which seems less ergonomic and deviates from common web development conventions.

Request for Feedback

I would like to understand the reasoning behind this design choice:

• Are there specific technical considerations that necessitate the action prop being mandatory in this case?
• Would it be possible to adjust the implementation to make the action prop optional, thereby aligning next/form more closely with the behavior of standard HTML forms?

This adjustment could enhance developer experience by reducing confusion and making the API more intuitive.

Suggested Improvements

• Make the action prop optional for the next/form component.
• Ensure that when the action prop is omitted, the behavior defaults to appending search parameters to the current route, similar to standard HTML form behavior.

Looking forward to your thoughts and any insights from the Next.js team on this matter.