var stream = require("stream");

var duplexer3 = require("duplexer3");

var writable = new stream.Writable({objectMode: true}),
    readable = new stream.Readable({objectMode: true});

writable._write = function _write(input, encoding, done) {
  if (readable.push(input)) {
    return done();
  } else {
    readable.once("drain", done);
  }
};

readable._read = function _read(n) {
  // no-op
};

// simulate the readable thing closing after a bit
writable.once("finish", function() {
  setTimeout(function() {
    readable.push(null);
  }, 500);
});

var duplex = duplexer3(writable, readable);

duplex.on("data", function(e) {
  console.log("got data", JSON.stringify(e));
});

duplex.on("finish", function() {
  console.log("got finish event");
});

duplex.on("end", function() {
  console.log("got end event");
});

duplex.write("oh, hi there", function() {
  console.log("finished writing");
});

duplex.end(function() {
  console.log("finished ending");
});

got data "oh, hi there"
finished writing
got finish event
finished ending
got end event

$ npm i duplexer3

duplexer3([options], writable, readable)

const duplex = duplexer3(new stream.Writable(), new stream.Readable());