Question: Are there any client-side validation gems similar to client\_side\_validations (https://github.com/bcardarella/client\_side\_validations) for Rails 2.x?

Answer: 
I am actually in the process of backporting the current ClientSideValidations gem to Rails 2.x

<https://github.com/bcardarella/client_side_validations-rails_2>

It's not ready for public consumption yet, but you might want to keep an eye on it. It will inherit from the current gem and add the necessary functionality to Rails 2.x.
Here is a project for [client side validations for rails 2](https://github.com/dnclabs/client_side_validations), it seems to be the same project that the one you refer but it was left in order to give full functionality to rails 3. There is also an [example for rails 2](https://github.com/dnclabs/client_side_validations_examples).

I recommend to check a great tutorial using [jquery validations with rails](http://sleekd.com/tutorials/jquery-validation-in-ruby-on-rails/).

Hope this helps.