Error Handling Patterns: Building Resilient Node.js Applications

Proper error handling distinguishes production-ready applications from prototypes. This guide covers error handling patterns for Node.js and TypeScript applications.

Custom Error Classes#

Error Hierarchy#

Result Type Pattern#

Type-Safe Error Handling#

With neverthrow Library#

Express Error Handling#

Async Handler Wrapper#

Global Error Handler#

Retry Patterns#

Exponential Backoff#

Circuit Breaker#

Process-Level Error Handling#

Best Practices#

1. Use typed errors: Create specific error classes for different scenarios
2. Don't swallow errors: Always handle or propagate errors
3. Log with context: Include request IDs, user IDs, and relevant data
4. Fail fast: Validate inputs early and throw immediately
5. Be consistent: Use the same error format throughout your API
6. Provide actionable messages: Help users understand what went wrong

Conclusion#

Good error handling makes applications maintainable and debuggable. Use custom error classes for type safety, implement proper async handling, and ensure graceful degradation. Remember to handle both expected errors (validation, not found) and unexpected ones (bugs, infrastructure failures).