Submit HTML form on self page

I want an HTML form to submit to itself. How do I use the action attribute?

1. <form action="">
2. <form action="#">
3. <form action="some/address">
4. <form>

Which was is preferable?

In 2013, with all the HTML5 stuff, you can just omit the 'action' attribute to self-submit a form

<form>

Actually, the Form Submission subsection of the current HTML5 draft does not allow action="" (empty attribute). It is against the specification.

From this other Stack Overflow answer.

Use ?:

<form action="?" method="post">

It will send the user back to the same page.

You can leave action attribute blank. The form will automatically submit itself in the same page.

<form action="">

According to the w3c specification, action attribute must be non-empty valid url in general. There is also an explanation for some situations in which the action attribute may be left empty.

> The action of an element is the value of the element’s formaction attribute, if the element is a Submit Button and has such an attribute, or the value of its form owner’s action attribute, if it has one, or else the empty string.

So they both still valid and works:

<form action="">
<form action="FULL_URL_STRING_OF_CURRENT_PAGE">

If you are sure your audience is using html5 browsers, you can even omit the action attribute:

<form>

If you are submitting a form using php be sure to use:

action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"

for security.

You can do it using the same page on the action attribute: action='<yourpage>'