Case Study: Refactoring a Feature at Scale

Most mature React applications eventually accumulate a component that becomes difficult to maintain. A widget that starts as a simple prototype can grow into a large, monolithic component packed with unrelated concerns, tangled useEffect calls, deeply nested state logic, and complex prop chains. At this stage, the issues are no longer limited to code organization. The component becomes fragile, harder to reason about, and risky to extend without introducing regressions. Effective refactoring starts by re-establishing clear boundaries between behavior, state logic, and presentation.

The layered refactoring sequence

Refactoring a monolithic component requires dismantling it into well-defined architectural layers. The transformation follows a deliberate sequence:

1. Extract state: Move useState, useEffect, and other behavioral bindings into a headless Hook, isolating all non-visual logic from the UI.

2. Isolate complexity: If transitions are branching or multi-step, migrate them from the hook into a reducer, creating a predictable, testable state machine.

3. Democratize data: Replace prop drilling with context, allowing multiple UI parts to consume the same behavior without manually passing props through the component tree.

4. Simplify render: Break the UI into compound components that subscribe to context and reflect state declaratively, without duplicating logic or manually wiring handlers.

This sequence ensures that each responsibility has a designated home: transitions in the reducer, behavior in the Hook, data distribution in the context, and semantics in compound components.

From monolith to layers

The diagram above illustrates the migration path from a tightly coupled component to a layered system. The headless Hook encapsulates the widget’s business logic and state transitions. Context is ...