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Allow to await writable streams #19068
Description
With async iterators, we can use synchronous-looking code to consume readable streams.
There is no equivalent for writable streams in Node core.
Example use case:
const fs = require('fs');
const zlib = require('zlib');
(async () => {
const read = fs.createReadStream('data.txt.gz');
const gunzip = zlib.createGunzip();
const write = fs.createWriteStream('data.txt');
await read.pipe(gunzip).pipe(write);
})();This would resolve when write ends or reject if an error occurs.
Prior art:
- https://github.com/bendrucker/stream-to-promise
- https://github.com/epeli/node-promisepipe
- https://github.com/dex4er/js-promise-writable
/cc @nodejs/streams @mcollina
Activity
mcollina commentedon Mar 1, 2018
This is currently not possible because of how error handling work in streams.
However, wrapping #13506 (
stream.pump) in a promise should be simple to do. I think we should work on landing that first, and then adding a promisified version of that too (orutil.promisify()).mafintosh commentedon Apr 6, 2018
Will be possible with the new pipeline api (based on pump) in #19828 and util.promisify, assuming it lands at it's current form
targos commentedon Apr 17, 2018
Fixed in #19828