Error Handling 🛡️

Plan for failures so your app can recover gracefully.

1) try/catch/finally 🔁

try {
  const data = JSON.parse(payload);
  process(data);
} catch (error) {
  console.error("Parsing failed", error);
} finally {
  cleanup();
}

• catch receives the thrown error.
• finally runs regardless of success/failure.

2) Throwing Errors 🚨

function assert(condition, message) {
  if (!condition) {
    throw new Error(message);
  }
}

• Throw built-in errors (Error, TypeError, RangeError) or custom subclasses.

3) Custom Errors 🎯

class ValidationError extends Error {
  constructor(message) {
    super(message);
    this.name = "ValidationError";
  }
}

• Add context (name, metadata) for smarter error handling.

4) Debugging Techniques 🧰

• console.log, console.table, console.group for quick inspection.
• Browser DevTools breakpoints, watches, and call stack inspection.
• Node.js --inspect mode to debug server scripts.

5) Promise Rejection Handling ⚠️

• Always .catch or use top-level window.addEventListener("unhandledrejection", ...) to log unexpected rejections.
• With async/await, wrap calls in try...catch.

Key Takeaways ✅

• Use try/catch for synchronous code; async code needs .catch or try/await.
• Throw meaningful errors to guide callers.
• Lean on DevTools to pause, inspect, and understand control flow.

Recap 🔄

Robust JavaScript apps expect errors: validate inputs, throw helpful messages, catch failures early, and use debugging tools to trace issues faster.