Is it a good practice to use an empty URL for a HTML form's action attribute? (action="")

Question

I am wondering if anyone can give a "best practices" response to using blank HTML form actions to post back to the current page.

There is a post asking what a blank HTML form action does here and some pages like this one suggest it is fine but I'd like to know what people think.

Answer 1

The best thing you can do is leave out the action attribute altogether. If you leave it out, the form will be submitted to the document's address, i.e. the same page.

It is also possible to leave it empty, and any browser implementing HTML's form submission algorithm will treat it as equivalent to the document's address, which it does mainly because that's how browsers currently work:

8. Let action be the submitter element's action.

9. If action is the empty string, let action be the document's address.

Note: This step is a willful violation of RFC 3986, which would require base URL processing here. This violation is motivated by a desire for compatibility with legacy content. [RFC3986]

This definitely works in all current browsers, but may not work as expected in some older browsers ("browsers do weird things with an empty action="" attribute"), which is why the spec strongly discourages authors from leaving it empty:

The action and formaction content attributes, if specified, must have a value that is a valid non-empty URL potentially surrounded by spaces.