How to Manage Unhandled Exceptions and Promise Rejections in JavaScript and React

Robust production applications require multi-layered error handling strategies beyond what typical demo apps provide. Synchronous errors can be caught using try...catch blocks, while asynchronous promise rejections must be handled with .catch() or try...catch alongside async/await. React Error Boundaries address rendering and lifecycle errors at the component level, though they do not cover event handlers, async errors, or promise rejections, which must be managed separately. Global browser listeners such as window.onerror and window.onunhandledrejection help capture any errors that slip through local handling. In production environments, developers are advised to integrate monitoring tools like Sentry or Datadog instead of relying solely on console.error, enabling stack traces, session data, and release tracking.