Big update!Introducing GitHub Bot Commands. Learn more
Log inBook a demo


Package Overview
File Explorer

Advanced tools


Turn a writable and readable stream into a streams2 duplex stream with support for async initialization and streams1/streams2 input


Version published
Weekly downloads
decreased by-11.39%

Weekly downloads




Turn a writeable and readable stream into a single streams2 duplex stream.

Similar to duplexer2 except it supports both streams2 and streams1 as input and it allows you to set the readable and writable part asynchronously using setReadable(stream) and setWritable(stream)

npm install duplexify

build status


Use duplexify(writable, readable, streamOptions) (or duplexify.obj(writable, readable) to create an object stream)

var duplexify = require('duplexify') // turn writableStream and readableStream into a single duplex stream var dup = duplexify(writableStream, readableStream) dup.write('hello world') // will write to writableStream dup.on('data', function(data) { // will read from readableStream })

You can also set the readable and writable parts asynchronously

var dup = duplexify() dup.write('hello world') // write will buffer until the writable // part has been set // wait a bit ... dup.setReadable(readableStream) // maybe wait some more? dup.setWritable(writableStream)

If you call setReadable or setWritable multiple times it will unregister the previous readable/writable stream. To disable the readable or writable part call setReadable or setWritable with null.

If the readable or writable streams emits an error or close it will destroy both streams and bubble up the event. You can also explicitly destroy the streams by calling dup.destroy(). The destroy method optionally takes an error object as argument, in which case the error is emitted as part of the error event.

dup.on('error', function(err) { console.log('readable or writable emitted an error - close will follow') }) dup.on('close', function() { console.log('the duplex stream is destroyed') }) dup.destroy() // calls destroy on the readable and writable part (if present)

HTTP request example

Turn a node core http request into a duplex stream is as easy as

var duplexify = require('duplexify') var http = require('http') var request = function(opts) { var req = http.request(opts) var dup = duplexify(req) req.on('response', function(res) { dup.setReadable(res) }) return dup } var req = request({ method: 'GET', host: '', port: 80 }) req.end() req.pipe(process.stdout)



duplexify is part of the mississippi stream utility collection which includes more useful stream modules similar to this one.



What is duplexify?

Turn a writable and readable stream into a streams2 duplex stream with support for async initialization and streams1/streams2 input

Is duplexify popular?

The npm package duplexify receives a total of 11,860,539 weekly downloads. As such, duplexify popularity was classified as popular.

Is duplexify well maintained?

We found that duplexify demonstrated a not healthy version release cadence and project activity because the last version was released a year ago.It has 1 open source maintainer collaborating on the project.

Last updated on 21 Jul 2021

Did you know?

Socket installs a Github app to automatically flag issues on every pull request and report the health of your dependencies. Find out what is inside your node modules and prevent malicious activity before you update the dependencies.

Install Socket


Subscribe to our newsletter

Get open source security insights delivered straight into your inbox. Be the first to learn about new features and product updates.

  • Terms
  • Privacy
  • Security

Made with ⚡️ by Socket Inc