I have a form
Unfortunately, what you are trying to do is not possible. The best you can do is probably this:
A submit button is displayed when client side scripting is disabled. When it's enabled, the submit button is immediately hidden and the form is automatically submitted.
EDIT
Or you could simply include the PHP file. . You won't have access to the
_POST
array, but considering, the client hasn't had chance to enter any data, that won't really matter.