Processing Large Files with Node.js Streams

Back to all nuggets
Node.js javascript

Published on July 14, 2026

Code Snippet

const fs = require("fs");
const zlib = require("zlib");
const { pipeline } = require("stream/promises");
const { Transform } = require("stream");

// Uppercase each chunk as it flows through
const upper = new Transform({
  transform(chunk, _enc, cb) {
    cb(null, chunk.toString().toUpperCase());
  },
});

async function run() {
  await pipeline(
    fs.createReadStream("input.txt"),
    upper,
    zlib.createGzip(),
    fs.createWriteStream("output.txt.gz")
  );
  console.log("Done — low memory, any file size.");
}

run().catch(console.error);

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Lorem ipsum dolor sit amet, consectetur adipiscing elit.

Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Premium Content Locked

Subscribe to unlock the full article, detailed explanations, and downloadable resources.

Subscribe to Read Full

Love this nugget?

Support our work to get exclusive premium nuggets and early access via a personal activation link.

Support Now & Unlock Exclusive Content