Error Handling in Node.js

Learn how errors work in JavaScript: runtime errors, throwing errors, try-catch-finally, custom errors, and safe error handling patterns.

Introduction to Errors

Errors occur when JavaScript cannot execute code as expected. Errors immediately stop normal execution unless they are handled.

Execution failure.

JavaScript provides multiple built-in error types to describe different failure scenarios.

Accessing undeclared variables.

Invalid operations on values.

Invalid JavaScript syntax.

Invalid numeric ranges.

try-catch allows handling runtime errors without crashing the program.

Prevent crashes.

Access error details.

finally executes whether an error occurs or not.

Always runs.

throw allows you to stop execution and signal failure explicitly.

Create custom failure.

Custom errors improve clarity and allow fine-grained error handling.

Define your own error.

Errors bubble up the call stack until caught.

Unhandled errors travel upward.

A stack trace shows the sequence of function calls that led to an error. It is one of the most important debugging tools.

Execution history.

Access stack trace programmatically.

Bottom-up execution.

Practical debugging.