Testing to see if user has JS enabled

By using a hidden field

[Jeremy_H]

I'm writing a form that uses JavaScript as the first level of authentication of input values.

Therefore, I'm interested in knowing if people that fill out the form have JavaScript enabled.

I'm thinking of using some code like below, but I noticed that even if I have JavaScript disabled, I still get "yes". Therefore its giving me some false positives.

Any idea how I can do this better? I'm using PHP if its of any consequence.

Thanks

<script type="text/javascript">document.write("<input type='hidden' name='js' value='yes'>")</script>

[Key_Master]

Designing documents for user agents that don't support scripting [w3.org]

[Bernard Marx]

but I noticed that even if I have JavaScript disabled, I still get "yes".

I can't see how that can happen with JS disabled.

[Fotiman]

Unless, of course, you had javascript enabled when the page loaded, but disabled when you submited the form.

[Bernard Marx]

Indeed.