Node.js Streams

A stream processes data in chunks instead of loading it all at once. This matters for big files and network data.

ExampleNode.js

const { Readable, Transform, Writable } = require("stream");
const { pipeline } = require("stream/promises");

const source = Readable.from(["alpha ", "beta ", "gamma"]);
const upper = new Transform({
  transform(chunk, enc, cb) {
    cb(null, chunk.toString().toUpperCase());
  },
});
const parts = [];
const sink = new Writable({
  write(chunk, enc, cb) {
    parts.push(chunk.toString());
    cb();
  },
});

pipeline(source, upper, sink).then(() => {
  console.log(parts);
  console.log(parts.join(""));
});

Output

[ 'ALPHA ', 'BETA ', 'GAMMA' ]
ALPHA BETA GAMMA

Quick check

Why use streams for large files?

They process data in chunks without loading everythingThey compress filesThey are required for fs

Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.

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