The <html:javascript> tag to allow front-end validation based on the xml in validation.xml. For example the code:
<html:javascript formName=\"logonForm\" dynamicJavascript=\"true\" staticJavascript=\"true\" />
generates the client side java script for the form \"logonForm\" as defined in the validation.xml file. The <html:javascript> when added in the jsp file generates the client site validation script.
