In the context of the MVC (Model-View-Controller) architecture for a Lightning Web Component (LWC), the Apex class and JavaScript file are responsible for handling the controller's role:
Apex Class (Controller):
Acts as the server-side controller.
Executes business logic, such as the complex validations mentioned in the scenario.
Exposes methods for the LWC to call using@AuraEnabled.
Reference:https://developer.salesforce.com/docs/component-library/documentation/en/lwc/lwc.apex JavaScript File (Controller):
Acts as the client-side controller.
Manages the interaction between the HTML (View) and Apex methods.
Executes functions triggered by user actions, such as clicking the "Validate" button.
Reference:https://developer.salesforce.com/docs/component-library/documentation/en/lwc/lwc.
js_props_methods
Why Not the Other Options?A. HTML file: Represents the "View" in MVC, focusing on UI rendering.
D). XML file: Used for metadata configuration and is not part of the controller functionality.