Push streams

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push

History

push(...transforms?, options?): Object

Attributes

...transforms:Function | Object

Optional transforms applied to the readable side.

options:Object

budget?:number

Maximum number of buffered bytes before backpressure is applied. Must be >= 16384. Default: 16384.

backpressure?:string

Backpressure policy: 'strict', 'unbounded', 'drop-oldest', or 'drop-newest'. Default: 'strict'.

signal:AbortSignal

Abort the stream.

Returns:Object

writer:Writable

The writer side.

readable:AsyncIterable

whose chunks fulfill with Uint8Array[]

Create a push stream with backpressure. The writer pushes data in; the readable side is consumed as an async iterable.

import { push, text } from 'node:stream/iter';

const { writer, readable } = push();

// Producer and consumer must run concurrently. With strict backpressure
// (the default), awaited writes block until the consumer reads.
const producing = (async () => {
  await writer.write('hello');
  await writer.write(' world');
  await writer.end();
})();

console.log(await text(readable)); // 'hello world'
await producing;

JavaScript

const { push, text } = require('node:stream/iter');

async function run() {
  const { writer, readable } = push();

  // Producer and consumer must run concurrently. With strict backpressure
  // (the default), awaited writes block until the consumer reads.
  const producing = (async () => {
    await writer.write('hello');
    await writer.write(' world');
    await writer.end();
  })();

  console.log(await text(readable)); // 'hello world'
  await producing;
}

run().catch(console.error);

JavaScript

The writer returned by push() conforms to the [Writer interface][].