Explanation:

A Digital Developer is converting a pipeline to a JavaScript controller and wants to use the existing pipeline debugger (configured in UX Studio) with the new controller, including adding a breakpoint. In Salesforce B2C Commerce, the debugger in UX Studio (now part of Salesforce Commerce Cloud development tools) is used to step through and debug both pipelines and JavaScript controllers. Since the pipeline debugger is already functioning, it can be adapted for the new controller with some configuration changes. Let’s evaluate the options:

A. Create and use a new script debug configuration.
Why incorrect: While script debugging is possible, the existing pipeline debugger can be modified to handle JavaScript controllers. Creating a new script debug configuration is unnecessary when the current setup can be adjusted.

B. Use the existing pipeline debugger.
Why incorrect: The existing pipeline debugger is configured for pipelines, not JavaScript controllers. Using it without modification won’t work for the new controller, as the debugging context (e.g., entry points, script files) differs.

C. Modify the debugger configuration and use the existing pipeline debugger.
Why correct: The Developer can modify the existing debugger configuration in UX Studio to point to the new JavaScript controller file (e.g., updating the script path or entry point to the controller). This allows the use of breakpoints and debugging features for the controller, leveraging the functioning pipeline debugger setup. The process involves adjusting the debug configuration to reflect the controller’s location and ensuring the site’s cartridge path includes the controller’s cartridge.
Reference: The UX Studio Debugging Documentation indicates that the debugger can be reconfigured for different script types, including controllers.

D. Create and use a new controller debug configuration.
Why incorrect: While a new configuration could be created, it’s inefficient when the existing pipeline debugger can be modified. Reusing and adjusting the current setup is the standard approach.

Why Option C:
The existing pipeline debugger can be adapted by modifying its configuration (e.g., script file path, breakpoints) to debug the JavaScript controller, saving time and leveraging the current setup.

Steps: Open UX Studio and access the existing debugger configuration.
Update the configuration to point to the new JavaScript controller file (e.g., controllers/MyController.js).
Add a breakpoint in the controller code.
Ensure the cartridge containing the controller is in the site’s cartridge path.
Start the debugger and test the controller.

Conclusion:
C is the correct step, allowing the Developer to use the existing pipeline debugger with the new controller after modification, as supported by the UX Studio Debugging Documentation.