How to check presence of Validation Errors on JSP at runtime

Hi,
In my application, I want to fire a JS function at runtime only when there are no validation errors on JSP.
In other words, if all required fields are filled with valid data by the user, then on-click of Next button which opens next page, I want to fire a JS function.

I am using Java 1.6 & Struts validation Framework.

Can anybody please help me on this.. ?
Thanks in advance…