Check if form is filled before submitting - php

Question

I have a form called choose_dates.php that submits to a file called process.php. The form consists of a textbox, a dropdown list and a submit button. I have set it up so that you can submit either one value, or the other, or both at the same time. I would like to have it such that if the user has put a value in the textbox AND the dropdown list, then a prompt will ask if that is what he/she really wants to do. The code below doesn't seem to do that when the submit button is pressed. The rest of my code (that I have not placed on here) works fine, this is more of a user interface issue.
<form name="dates" action="process.php" method="POST">
<input type="text" name="submitDate">
<select name="removeException">
<option value="some-value">display dropdown stuff</option>
.
.
</select>
<input type="submit" value="submit"
<?php
if($_POST['submitDate'] != "" and $_POST['removeException'] != "")
{
echo " onclick=\"return confirm('Are you sure you want to submit both values at the same time?')\" ";
}
?>
tabindex="2">
</form>
And of course, please ask any questions if what I said isn't clear enough. Regards.

Answer 1

Add onsumbit="return checks();" in form tag.
checks is a Javascript function that verify everything is good, if not, return false and the form will not be submited. If true, the form will be submited normally. just move your onclick to onsumbit in form.

Answer 2

You need to do that on the client side using javascript ( preferably ). The post data will be submitted when the form is submitted. Try adding this function as your form's onsubmit event
function func(){
var a = document.getElementsByName('removeException'),
b = document.getElementsByName('submitDate');
if(a[0].value!=null && b[0].value!=null){
var c = confirm('Are you sure you want to submit both values at the same time?')
if(c){
return true;
}else{
return false;
}
}
}
Then
<form name="dates" action="process.php" method="POST" onSubmit='return func()'>