node:stream

node:stream, node:stream/promises, and node:stream/consumers match Node’s streams.

Example

// stream.mjs
import { Readable, Transform, Writable } from "node:stream";
import { pipeline } from "node:stream/promises";

const upper = new Transform({
  transform(chunk, _encoding, done) {
    done(null, chunk.toString().toUpperCase());
  },
});
const lines = [];
const sink = new Writable({
  write(chunk, _encoding, done) {
    lines.push(chunk.toString());
    done();
  },
});

await pipeline(Readable.from(["alpha", "beta", "gamma"]), upper, sink);
console.log(lines.join(" "));

utf-8 · js · Lines: 19

elide run stream.mjs prints:

text

ALPHA BETA GAMMA

utf-8 · text · Lines: 1

Differences from Node

node:stream/web classes are the same objects as the WHATWG stream globals.
node:stream/iter is an Elide extension with iterator conversion helpers.

Samples

Reference

Status: Partial · 215 of 238 suite tests pass (90.3%) · since 1.1.0

Exports

Export	Kind	Status	Notes
`Readable`	class	Full	`readable`, `readableEnded`, `readableFlowing`, `readableHighWaterMark`, `readableLength`, `readableObjectMode`, `readableEncoding`, `destroyed`, `read()`, `setEncoding()`, `pause()`, `resume()`, `isPaused()`, `unpipe()`, `unshift()`, `wrap()`, `push()`, `destroy()`, `pipe()`, `toArray()`, `forEach()`, `some()`, `every()`, `find()`, `reduce()`, `map()`, `filter()`, `flatMap()`, `drop()`, `take()`
`Writable`	class	Full	`writable`, `writableEnded`, `writableFinished`, `writableHighWaterMark`, `writableLength`, `writableObjectMode`, `writableCorked`, `destroyed`, `write()`, `end()`, `cork()`, `uncork()`, `destroy()`, `setDefaultEncoding()`
`Duplex`	class	Full	`writable`, `writableEnded`, `writableFinished`, `writableHighWaterMark`, `writableLength`, `writableObjectMode`, `writableCorked`, `write()`, `end()`, `cork()`, `uncork()`, `setDefaultEncoding()`
`Transform`	class	Full
`PassThrough`	class	Full
`Readable`	property	Full	The Readable stream class
`Writable`	property	Full	The Writable stream class
`Duplex`	property	Full	The Duplex stream class
`Transform`	property	Full	The Transform stream class
`PassThrough`	property	Full	The PassThrough stream class
`pipeline`	property	Full	Promise-based pipeline() utility for composing stream pipelines with error propagation
`finished`	property	Full	Promise-based finished() utility that resolves/rejects when a stream completes or errors
`compose`	property	Full	Composes streams into a single Duplex; pipes them and returns a Duplex that writes to the head and reads…

Not implemented

stream/web.ReadableStreamTee.

Tests: node-api node:streams: 215 pass, 22 fail, 1 error, 9 skipped. Failing: test-stream-auto-destroy.js, test-stream-compose.js, test-stream-consumers.js, test-stream-destroy.js, test-stream-duplex-from.js, test-stream-duplex.js, test-stream-iter-disabled.js, test-stream-iter-readable-interop-disabled.js, and 15 more.