Error Handling Patterns

Error Categories

Recoverable Errors

Can be handled and recovered from.

File not found → Try alternate location
Network timeout → Retry with backoff

Unrecoverable Errors

Application cannot continue, must fail fast.

Out of memory
Invalid license key

Error Handling Patterns

Try-Catch-Finally

Traditional approach for exception handling.

try {
  // risky operation
} catch (error) {
  // handle error
} finally {
  // cleanup
}

Result Type

Functional approach, error as return value.

const result = operation();
if (result.isError) {
  // handle error
} else {
  // use value
}

Callback with Error

Node.js convention.

fs.readFile('file.txt', (error, data) => {
  if (error) {
    // handle error
  } else {
    // use data
  }
});

Retry Strategies

Exponential Backoff

Increase wait time between retries.

Wait 1s, then 2s, then 4s, then 8s...

Jitter

Add randomness to prevent thundering herd.

Wait (1s * random(0-1)) before retry

Circuit Breaker

Stop retrying after threshold failures.

3 failures → open circuit → fail fast

Best Practices

• Fail fast and clearly
• Log errors with context
• Don't swallow exceptions silently
• Use specific error types
• Provide meaningful error messages
• Implement proper cleanup
• Test error paths
• Monitor error rates and patterns