ReactJS Practice Test

Error boundaries focus on protecting the UI from render-time errors by catching exceptions that occur while a part of the component tree renders, in the lifecycle methods, or in constructors of child components. When such an error happens, the boundary renders a fallback UI instead of crashing the whole app, so users see something graceful while the rest of the interface remains usable. They do not catch errors in event handlers, so errors thrown inside click or submit handlers aren’t handled by the boundary—you’d handle those inside the event handler itself or with local try/catch. Error boundaries are implemented as class components that define componentDidCatch and, optionally, getDerivedStateFromError; they are not hooks-based. They do not fix errors automatically; they merely provide a safe fallback UI when an error occurs.