Watching files for changes in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of watching files for changes in Node.js?

Watching files for changes lets your program notice when a file is updated, added, or deleted. This helps automate tasks like reloading code or updating content without manual checks.

beginner

Which Node.js module is commonly used to watch files for changes?

The built-in fs module provides methods like fs.watch() and fs.watchFile() to watch files or directories for changes.

intermediate

What is the difference between fs.watch() and fs.watchFile()?

fs.watch() uses the operating system's native watching and is more efficient but less consistent across platforms. fs.watchFile() uses polling, checking the file at intervals, which is more consistent but can use more resources.

beginner

How do you stop watching a file using fs.watch()?

The fs.watch() method returns a watcher object. You call watcher.close() on this object to stop watching the file.

intermediate

Why is it important to handle errors when watching files?

Errors can happen if the file is deleted or permissions change. Handling errors prevents your program from crashing and lets you respond gracefully, like restarting the watcher or notifying the user.

Which Node.js method uses polling to watch files?

A fs.open()

B fs.watchFile()

C fs.readFile()

D fs.watch()

fs.watchFile() uses polling to check for file changes at intervals.

How do you stop watching a file with fs.watch()?

A Call watcher.close()

B Call fs.unwatch()

C Call fs.stop()

D Call watcher.stopWatching()

The watcher object returned by fs.watch() has a close() method to stop watching.

What event does fs.watch() emit when a file changes?

A "fileChanged"

B "update"

C "modify"

D "change"

fs.watch() emits a "change" event when the watched file or directory changes.

Which of these is NOT a benefit of watching files for changes?

A Manually checking files every minute

B Automatically reload code on changes

C Triggering tasks when files update

D Improving development workflow

Manually checking files is the opposite of watching files automatically.

What should you do if the watched file is deleted?

A Delete the watcher object without closing

B Ignore it and continue watching

C Handle the error and possibly restart watching

D Restart the whole Node.js process

Handling errors when files are deleted helps keep your program stable and responsive.

Explain how to watch a file for changes in Node.js using the fs module.

Think about the methods and how to start and stop watching.

Describe the differences between fs.watch() and fs.watchFile() and when you might use each.

Consider efficiency versus consistency.