Form validation: PHP or Javascript?

[ozchris]

Hi.

I'm still at beginner mode for PHP and Javascript, working out of books.

If I have a form on a page, and I want to validate the 2 input fields, and display the result in a third field, is it best to use Javascript or PHP?

The rest of the site is already using PHP for menu includes.

With PHP, how do you make the result stay on the same page? So far I've only practised pages that go to a new page when you hit submit.

What percentage of people/browsers would have Javascript disabled? - is it generally worth excluding Javascript function if there is an alternative work around?

ta Chris

[mushroom]

Originally Posted by ozchris

If I have a form on a page, and I want to validate the 2 input fields, and display the result in a third field, is it best to use Javascript or PHP?

With PHP, how do you make the result stay on the same page? So far I've only practised pages that go to a new page when you hit submit.

What percentage of people/browsers would have Javascript disabled?

1. Use php and keep it server side.
2. refer page back to itself and use if (isset($var1) and isset($var2)) {to change output:}
3. http://www.w3schools.com/browsers/browsers_stats.asp

[Corey Bryant]

I agree - the more server side coding you can use - the less chances you have something worrying about wiht the way the browser will (not) handle your coding.

[ozchris]

Thanks mushroom.

I found onlamp.com, which had a great example on what you suggest.

I have put my first version at
http://womens-health-and-fitness.com...mass-index.php

Problems so far:
1. It seems to reset the input values to blanks when it redisplays the screen.
2. When you try to refresh the screen, you get the message 'cannot refresh, retry or cancel'. Is that normal with forms calling the same page?
3. I couldnt test this offline. I have e-novative's WAMP environment on my PC to test PHP, and this exact code would NOT process the isset command offline. I had echos coming out of my seat trying to see why it wouldn't go into my if statement. After 2 hours I uploaded it and it worked. Is this normal for offline PHP environments?

I put the php code immediately above the form, as follows:

<?

$bminum = "";
$bmitext = "";

if (isset($metric_bmi_entered)) {
$height = $_POST["bheight"];
$weight = $_POST["bweight"];

$squareheight = $height * $height;
$bmi = $weight / $squareheight;

$bminum = sprintf ("%1.2f", "$bmi");

if ($bminum < 18.5) {
$bmitext = "underweight"; }
elseif ($bminum < 25) {
$bmitext = "normal" ; }
elseif ($bmitext < 30) {
$bmitext = "overweight"; }
else { $bmitext = "obese";}
}
?>

I spent time looking at the php switch command, but couldn't see how to put a range of values, or >< in the case statement. Definite beginner.

ta Chris

[ADAM Web Design]

I would suggest "both".

This would give you the benefit of reducing calls to your server for form validation when it isn't necessary (i.e. when the user has Javascript enabled), while providing a backup plan in case someone has it disabled.

[paulhiles]

I would agree with Adam here, client-side Javascript is both quick and extremely effective for the vast majority of site visitors.

However, if a visitor chooses not to enable Javascript for whatever reason, then there should be server-side error-handling to catch these users too!

Paul

[imported__sam_]

Originally Posted by ozchris

3. I couldnt test this offline. I have e-novative's WAMP environment on my PC to test PHP, and this exact code would NOT process the isset command offline. I had echos coming out of my seat trying to see why it wouldn't go into my if statement. After 2 hours I uploaded it and it worked. Is this normal for offline PHP environments?

Hello Chris,

The reason for that is most likely a PHP setting called REGISTER_GLOBALS, see http://at2.php.net/register_globals

In order not to rely on this setting, use $_POST['metric_bmi_entered'] instead of $metric_bmi_entered.

Originally Posted by ozchris

I spent time looking at the php switch command, but couldn't see how to put a range of values, or >< in the case statement.

That's not possible in PHP. You can do this, but that's not really the intended use of switch:

switch (TRUE) {
  case ($bminum < 18.5):
  ...
}

best regards

- Sam