Working with Modules and Handling Exceptions

Estimated study time: 7 minutes. Two habits that separate fragile scripts from production-ready code.

Two skills quickly separate beginner code from production-ready code: organizing logic into modules, and handling things going wrong through exception handling.

Working with Modules

A module is simply a file (or group of files) that encapsulates a specific piece of functionality and exposes only what other parts of the app need. Good module design follows a few habits:

• One responsibility per module — a auth module handles authentication, not also formatting dates.
• Export only what's needed externally; keep internal helper functions private.
• Avoid circular dependencies — module A importing module B which imports module A again.

Handling Exceptions

Things fail at runtime — a network call times out, a file doesn't exist, user input is malformed. Exception handling lets your program respond to these failures without crashing entirely.

try {
  const data = JSON.parse(userInput);
  processData(data);
} catch (error) {
  console.error('Failed to process input:', error.message);
  showUserFriendlyError();
} finally {
  hideLoadingSpinner();
}

Best Practices for Exceptions

• Catch only what you can meaningfully handle — don't swallow errors silently.
• Use specific error types/messages so debugging doesn't turn into guesswork.
• Always clean up resources (connections, spinners, locks) in a finally block.
• Log enough context to reproduce the issue later.