stream.pipeline does not correctly work with process.stdout and stderr

[polomsky]

Version

24.6.0 22.18.0

Platform

Windows

Subsystem

No response

What steps will reproduce the bug?

Run in interactive mode (REPL)
stream.pipeline(fs.createReadStream('c:\\testfile.txt'), process.stdout)

How often does it reproduce? Is there a required condition?

always

What is the expected behavior? Why is that the expected behavior?

Expected behavior is that content of the file will be printed to STDOUT.

What do you see instead?

TypeError [ERR_INVALID_ARG_TYPE]: The "streams[stream.length - 1]" property must be of type function. Received an instance of WriteStream

Additional information

process.stdout is Stream, based on documentation of stream.pipeline destination is allowed to be Stream.

[juanarbol]

I get the idea, if that is blocking you, you could use pipe in the meantime.

'use strict'

const stream = require('stream')
const fs = require('fs')

fs.createReadStream(__filename)
  .pipe(process.stdout)

You can edit your script into this, and it is gonna work. Simply provide a callback, the problem is gone. But I guess there's a missing part in our docs, I'll ping @nodejs/streams in order to do the right updates in our docs, thanks for your report.

'use strict'

const stream = require('stream')
const fs = require('fs')

stream.pipeline(
  fs.createReadStream(__filename),
  process.stdout,
  (err) => {
    if (err) {
      console.error('Pipeline failed.', err)
    } else {
      console.log('Pipeline succeeded.')
    }
  }
)

[jakecastelli]

The pipeline method exists in two forms: the callback-based version exported from node:stream, and the promise-based version exported from node:stream/promises. If you're using the callback-based pipeline, you must pass a callback function as the last argument.

[polomsky]

I see, stream.pipeline is not promised version in REPL.