Lots! lol, but no, putting it in a PHP file makes no difference.
Code:
<script>
function checkDropDown(shipping) {
if(document.getElementById(shipping).value != 'none') {
return true;
}
else {
alert('Please select an item from the drop down');
return false;
}
}
</script>
<form method='POST' action='checkout2.php' onsubmit='return checkDropDown("shipping");'>
<br>
<select size='1' name='shipping' id='shipping' align='left'>
<option selected value=none>Select Shipping</option>
<option value=0.00>UPS Ground-FREE</option>
<option value=10.00>UPS1-$10.00</option>
<option value=20.00>UPS2-$20.00</option>
</select><br><br><input id='submit' type='button' value='Continue' onClick='validate()'></form>
I've highlighted the changes I made in red. One question I do have concerns validate(). Does this function submit the form? If it does, then it's all good. But if not, then you may still encounter a problem as you're not submitting the form any longer (that submit button is a NOT a submit button, but rather just a regular button).
Hope that helps,
Sadiq.