Writing to files is a common task in Node.js, whether for logging, saving uploads or creating reports. Node.js has various methods through the built-in fs (File System) module to write or append data both synchronously and asynchronously.

Method 1: Using fs.writeFile()

This creates or overwrites a file asynchronously:

js

const fs = require(‘fs’);fs.writeFile(‘output.txt’, ‘Hello eSparkBiz!’, (err) => {if (err) throw err;

console.log(‘File written successfully’);

});

Method 2: Using fs.appendFile()

Use this to add content to an existing file:

js

fs.appendFile(‘output.txt’, ‘\nMore content here…’, (err) => {if (err) throw err;

console.log(‘Content appended!’);

});

Method 3: Using Promises with fs.promises

Modern alternative for cleaner async code:

js

const fs = require(‘fs’).promises;async function writeFile() {

await fs.writeFile(‘output.txt’, ‘Written with promises!’);

}

writeFile();

Also Read: How To Update Node JS To Latest Version

Method 4: Using Writable Streams

Recommended for large data writes or continuous output:

js

const stream = fs.createWriteStream(‘bigfile.txt’);stream.write(‘Chunk 1\n’);

stream.end(‘Final chunk’);

Conclusion

Use fs.writeFile() or Promises for simple tasks. Use streams for writing large files in Node.js apps.