It's always suggested to use either a Java-backed controller or JavaScript-backed controller for a web script and both controllers should not be used together. However, let's take a look at some scenarios where you can leverage using both the controllers for a web script and solve some critical issues.

Consider a scenario where in a production system, you already have a web script that has a Java-backed controller extending DeclarativeWebScript and returns some output. Now, as a part of fixing a critical issue, there is a need to return additional information in the web script response and you did not have the option to restart the production server as server downtime could impact the customer business. In this scenario, you can write an additional JavaScript controller for your web script, set the additional information in the model object, and modify the response template to include the newly added information. Register the web script and web script should now...