`fs.createWriteStream()`

Creates a writable stream for incrementally writing to a file.

Since Node 0.x Spec ↗

Syntax

fs.createWriteStream(path[, options])

Parameters

Name	Type	Required	Description
`path`	`string \| Buffer \| URL`	Yes	The file to write.
`options`	`object \| string`	No	Encoding string, or object with `flags` (`'a'` to append), `encoding`, `mode`, and `start`.

Returns

fs.WriteStream — A Writable stream you write chunks to.

Examples

import { createWriteStream } from 'node:fs';

const log = createWriteStream('./app.log', { flags: 'a' });
log.write('request received\n');
log.end();

import { createReadStream, createWriteStream } from 'node:fs';
import { pipeline } from 'node:stream/promises';

await pipeline(
  createReadStream('./in.txt'),
  createWriteStream('./out.txt'),
);
console.log('copied');

Output

copied

Notes

Reuse a single append stream for high-volume logging instead of calling `appendFile` repeatedly. Respect backpressure: if `write()` returns false, wait for the `'drain'` event, or use `pipeline`.