Tell me about Feature Sliced Design (FSD): what is it and how have you applied it in a project?

Feature Sliced Design (FSD) is a methodology for organizing frontend code, focused on dividing the project by feature slices rather than technical layers.

The main idea is to split the application into independent, reusable, and isolated parts, each responsible for a specific business function. This facilitates scaling, support, and development of the project.

In FSD, the structure typically includes levels:

• App — the root level of the application.
• Pages — pages of the application.
• Features — functional capabilities that can be used across different pages.
• Entities — business entities with their logic and state.
• Shared — common utilities, components, and styles.

In my project, I applied FSD to improve modularity and reduce coupling. It helped the team work in parallel on different features without conflicts and simplified navigation through the code. For example, when adding new functionality, we created a separate slice in the features folder, which allowed isolating changes and testing them easily.

This approach is especially useful in large SPAs, where maintaining a clean architecture and scalability is important.