Best alternative for Bj plugin for rails 4?

I am upgrading Rails 2 application to Rails 4. I have successfully upgraded in rails 3. Now in Rails 4 Bj plugin is not supported. In my application on some pages Bj help to generate pdf on page load and some other pages Bj generate PDF when click on a button.

I already tried to convert Bj plugin as library for rails 4 but it not help me out.

Can any one give me solution what's the better alternative of Bj or how to upgrade BJ for Rails 4.

Thanks,