Category: React

Synchronize with external systems: fetch, subscriptions, timers, DOM APIs.

Provide defaults with default parameters (modern) or defaultProps (legacy).

Store component-local data that can change over time.

Add state to function components with useState.

Handle clicks, inputs, and submits with React synthetic events.

Render UI conditionally with &&, ternaries, or early returns.

Understand class components for legacy codebases.

Pass data into components via props (read-only inputs).

Pass strings, numbers, objects, arrays, and callbacks as props.

Write JSX with one parent, className, and self-closing tags.