How to Efficiently Append Data to Files in Node.js?

Appending to Files in Node.js

When attempting to append a string to a log file, using writeFile may result in erasing the existing content. To address this issue, Node.js provides alternative methods for appending data to files.

Easy Method: AppendFile

For occasional appends, appendFile can be employed. It creates a new file handle with each invocation:

Asynchronously:

const fs = require('fs');

fs.appendFile('message.txt', 'data to append', (err) => {
  if (err) throw err;
  console.log('Saved!');
});

Synchronously:

const fs = require('fs');

fs.appendFileSync('message.txt', 'data to append');

Efficient Method: Reusable File Handle

For repeated appends to the same file, it's more efficient to reuse a file handle. This approach involves opening a file handle once, executing multiple appends, and closing the handle when finished:

const fs = require('fs');

const fd = fs.openSync('message.txt', 'a'); // Open file for appending
fs.writeSync(fd, 'data to append', null, 'utf-8'); // First append
// ... subsequent appends
fs.closeSync(fd); // Close file handle

Note on Performance:

For a large number of appends, reusing a file handle significantly enhances performance compared to repeatedly calling appendFile. However, for infrequent appends, the convenience of appendFile may outweigh the performance benefits.

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