Error Handling

Things go wrong: a value is missing, a calculation doesn’t make sense, a user types something unexpected. This module covers how to catch problems before they crash your program, and how to signal your own errors clearly when something the caller needs to know about goes wrong.

Why This Matters

A program that crashes on the first bad input isn’t a finished program. Handling errors on purpose, rather than hoping they never happen, is what separates a script that works on the happy path from one that’s actually reliable.

What You’ll Learn

• Catching problems with try, catch, and finally
• Raising your own errors with throw
• Writing custom error classes by extending JavaScript’s built-in Error
• Best practices for deciding what to catch, what to let propagate, and what to log

Outcome

By the end of this module, you’ll be able to handle errors gracefully instead of letting your program crash, and communicate exactly what went wrong when it matters.

Let’s get started.