const DuplexPair = require('duplexpair');

const { socket1, socket2 } = new DuplexPair();

socket1.write('Hi');
console.log(socket2.read());  // => <Buffer 48 69>

// Or, using options that are passed to the Duplex constructor:

const { socket1, socket2 } = new DuplexPair({ encoding: 'utf8' });

socket1.write('Hi');
console.log(socket2.read());  // => 'Hi'