To validates the user input on the browser,validator Framework emits the JavaScript code. Follow these steps to accomplish this:

1. Enabling the Validator plug-in: This makes Validator available to the system itself.
2. Create Message Resources To display error message to the user.

3. Developing the Validation rulesIn validation.xml,we have to define the validation rules for the address form. Struts Validator Framework uses this rule for generating JavaScript for validation.

4. Applying the rules: For generation of JavaScript,we are required to add the appropriate tag to JSP.
5. Build and test: Before the testing,we are required to build the application once the above steps are done . 

Enabling the Validator plug- in is used to enable validator plug-in open the file struts-config.xml and make sure that following line is present in the file.

To generate the validation error,messagesMessage resources are used by Validator Framework . We need to define the message for name,Address and E-mail address in our application. Add following lines:

AddressForm.name=Name
AddressForm.address=Address
AddressForm.emailAddress=E-mail address
into the Struts\strutstutorial\web\WEB-INF\MessageResources.properties file.

We are adding only one validation that fields on the form should not be blank in this application. Add the following code in validation.xml to validate the form.

The above example defines validation for the form fields name, address and emailAddress. To check that the fields are not left blank,the attribute depends="required" is used to instructs Validator Framework to generate the JavaScript .JavaScript shows error message,if the fields are left blank .The message are taken from the key defined in <arg key=".."/> tag in the error message.We can take the value from message resources (Struts\strutstutorial\web\WEB-INF\MessageResources.properties).

To test the application just create AddressJavascriptValidation.jsp file . The following file called AddressJavascriptValidation.jsp is as follows:

To plug-in Validator JavaScript,the code <html:javascript formName="AddressForm"/> is used .

In struts-config.xml,create the following entry for the mapping the /AddressJavascriptValidation url for handling the form submission through AddressJavascriptValidation.jsp.

To call the form,add the following line in index.jsp.

Go to Struts\strutstutorial directory and type ant on the command prompt to build and deploy application. This will use to deploy the application.Then open the browser and navigate to AddressJavascriptValidation.jsp page. Your browser should shows the following output.

Browser shows the error message,if the fields are left blank and Save button is clicked,