Package Exports

duplexify

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Readme

duplexify

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 asynchroniously using setReadable(stream) and setWritable(stream)

npm install duplexify

Usage

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 asynchroniously

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 explictly destroy the streams by calling dup.destroy()

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: 'www.google.com',
  port: 80
})

req.end()
req.pipe(process.stdout)

License

MIT