Error Handling: try/catch/throw

8 min read

Error Handling

Errors are inevitable. Handling them gracefully — logging useful information, recovering where possible, and failing clearly — is the mark of production-ready code.

javascript

try {
  const result = riskyOperation();
  console.log(result);
} catch (error) {
  // `error` is an Error object with .message and .stack
  console.error("Something went wrong:", error.message);
} finally {
  // Always runs — use for cleanup (close files, stop spinners)
  cleanup();
}

Throwing Errors

javascript

function divide(a, b) {
  if (b === 0) throw new Error("Cannot divide by zero");
  return a / b;
}

// Custom error classes
class ValidationError extends Error {
  constructor(field, message) {
    super(message);
    this.name = "ValidationError";
    this.field = field;
  }
}

try {
  throw new ValidationError("email", "Invalid format");
} catch (e) {
  if (e instanceof ValidationError) {
    console.log(e.field, e.message); // email Invalid format
  } else {
    throw e; // re-throw unexpected errors
  }
}

Always re-throw errors you do not know how to handle. A caught-and-swallowed error is worse than a crash — it hides bugs and makes debugging nearly impossible.

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