I think i can do this in Javascript, (if not, point me to the right script), but how do you make it so that when a user presses the submit button on an html form, the script checks to make sure all the inputs have values before sending it to the action=""? Example: When signing up for a membership and you only enter your password once and forget to "verify" it, how does it create the alert() and say you need to fill in that field?

A function similar to that below will do it:

<script language="JavaScript">
function sub_check() {
	d = document.newsletter;
	if (d.email.value == "") { alert("Please enter an email address"); return(false) }
	URL = "subscribe.php?email="+e;
	window.location = URL;
}
</script>

You will, of course, need to change the form and field names to suit those you have used, and don't forget to use an opening <form> tag in the form of

<form action='' name='newsletter' id='newsletter' onSubmit='sub_check(); return(false)'>

Notice that the action is left blank in the form as the JavaScript actually takes care of that for you.

As Submit buttons can sometimes be a pain in the a** I always tend to use an image in the form:

<img src='images/subscribe.jpg' width='84' height='34' border='0' onClick='sub_check()'>

In case you are wondering why the routine is included in the <form> twice, this is done to ensure that people pressing the return key rather than clicking on the submit button are also sent via the error cheching routine.

I hope that clears things up for you.