is there a benefit to client-side input validation

if you're already doing server-side validation

[pixeltierra]

I already know that there is the benefit (obviously) of reduced server traffic. But I run low-traffic sites, and I'm just wondering if I'm missing something. Why run validation on both ends, as some people suggest, if you're already using server-side validation (besides traffic)?

[eelixduppy]

It gives an error to the user without having to submit the form first. It's just a nicer, faster way of notifying them of an error.

Of course you always need to double check with some server-side scripting.

[vincevincevince]

It's always nice to know what the problem is before having to wait for the page to reload. Especially when it means having to enter the password field again, every time.