What type of file stores custom code in SFCC?

In Salesforce Commerce Cloud (SFCC), custom code is primarily stored in JavaScript files. This is because the platform relies heavily on JavaScript to implement business logic, handle server-side functionality, and manage interactions between the frontend and backend. JavaScript files allow developers to create custom controllers, models, and scripts that enhance the functionality of the SFCC application.

JavaScript is essential for tasks such as creating APIs, managing data processing, and defining behaviors that are specific to your e-commerce application. The flexibility of JavaScript makes it an effective choice for building custom features and adapting the behavior of the storefront according to the unique requirements of the business.

Other file types like HTML, CSS, and XML serve different purposes within SFCC. HTML is used for markup and structure of the web pages, CSS is utilized for styling and layout, while XML might be used for configuration files or data interchange, but none of these serve as a medium for custom business logic or functionality in the way that JavaScript does. Thus, the use of JavaScript files is central to storing and executing custom code in SFCC.