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Frontend Resilience (Part 1): Defensive Programming and Error Boundaries

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Frontend Resilience (Part 1): Defensive Programming and Error Boundaries

When one component or one bad piece of data fails, the whole app shouldn't crash. Defensive programming (validating inputs, handling missing data) and error boundaries (catching render errors and showing a fallback) keep the app stable and give users a path forward. This post covers how to do both in a Vue or React-style frontend.

Why it matters

  • Resilience: A bug in a small widget (e.g. a comment list) shouldn't blank the entire page.
  • User trust: Showing a fallback or a clear message is better than a white screen or silent failure.
  • Debugging: Logging and reporting errors at a boundary makes it easier to find and fix the cause.

Validate at the edges

Treat inputs as untrusted: API responses, URL params, user input, props from parent. Validate or normalize before using.