We've got a form with default text values present within the text box itself which "goes away" when I click on them and enter a value (not if I dont enter a value). Currently the 'default' value or the user inputted value gets POSTed to the PHP script.

Should I have the javascript code check if the value being submitted is the default one and set it to "" (blank string) OR should I perform this check in PHP where I'll have to do a check if its "" OR if its to the default value.

Which is more efficient, having javascript clean up the data before sending it to PHP, or having PHP do the check itself?

One reason to keep it within PHP (though not a consideration for us at the moment) is so that we can display the default text labels in multiple languages, and check if the user has left them blank. That would be easier in PHP, I imagine?

  • You should consider the placeholder attribute, supported by all modern browsers (except IE) Aug 1, 2011 at 8:21

3 Answers 3


You need to do it on the server side w/ PHP. You cant rely that javascript was enabled on the client, or that nothing went wrong with it, or that the data sent to the server from the wilds of the interweb is in any way valid.

Ideally, you'd do it both in JavaScript on the client and in PHP on the server. Doing it in JavaScript might make the ui look more refined, but server-side validation and checking is a must.

  • "Doing it in JavaScript might make the ui look more refined" The purpose of client-side validation is instant feedback to the user, which in this case is not applicable or necessary.
    – Raynos
    Aug 1, 2011 at 7:14
  • Correct - but from a speed perspective, would it be faster for the javascript to 'blank it out' if its the default value, and then pass it to PHP? So I only have to do one check at the PHP level? Just trying to gain an understanding which approach would be faster... @GrandmasterB @Raynos?
    – siliconpi
    Aug 1, 2011 at 7:21
  • 2
    @matt74tm there is no noticable speed difference but please go read about server-side validation and security. Remember all customers/clients/users are evil and will hack your website. Can't trust any of them
    – Raynos
    Aug 1, 2011 at 7:26

You should do both.

Having to wait for the form to submit back and PHP do the processing and then re-perform a whole page load just to tell you, you forgot to enter something in a box is very poor user experience.

Firstly validate your form inputs in JavaScript, either manually or by using a jQuery Validate plugin to speed things up for you.

Once your form submits, then perform the validation in PHP. Remember that JS can be disabled, tweaked as it is a client-side technology. Always rely on the PHP but never have it as a default else your users will be subject to a poor user experience.

Good luck with your validation.

Regards, Paul Dragoonis.

  • javascript for UX (user experience)

  • php for security

both is the better, but javascript with improving user experience in mind, and php for securing your app in mind

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