How can you append data to an existing file in Node.js?

Q: How can you append data to an existing file in Node.js?

const fs = require('fs'); fs.appendFile('example.txt', 'Appended text.', 'utf8', (err) => { if (err) { console.error(err); return; } console.log('Data appended to the file.'); });

Difficulty: 6/10

File System (fs), Streams & I/O, Asynchronous JS

You can append data to an existing file in Node.js using the `fs.appendFile()` method. Here's an example:

javascript

Scenario Questions

0-2 years experience

1We have a simple Express route that needs to log incoming request IPs to a local 'access.log' file. How would you write the code to append each IP on a new line without overwriting the existing logs, and how would you handle it if the file doesn't exist yet?
2Imagine you used fs.writeFileSync to add a new user's email to a 'subscribers.txt' file, but you realized it keeps wiping out all the previous subscribers. What went wrong, and how would you fix it using the fs module?

Follow-up Questions

What is the difference in memory overhead between fs.appendFile and a WriteStream with the 'a' flag?
How does Node.js handle backpressure when writing to a stream?
What happens to the event loop if you use synchronous file append methods under high load?

How can you append data to an existing file in Node.js?

You can append data to an existing file in Node.js using the fs.appendFile() method. Here's an example:

Scenario Questions

Follow-up Questions

How can you append data to an existing file in Node.js?

You can append data to an existing file in Node.js using the fs.appendFile() method. Here's an example:

Scenario Questions

Follow-up Questions

You can append data to an existing file in Node.js using the `fs.appendFile()` method. Here's an example:

You can append data to an existing file in Node.js using the `fs.appendFile()` method. Here's an example: