One method to add as many mixins as you'd like to your NodeJS Classes

mixin.js

// Items we'd like to have mixed into our class
const { EventEmitter } = require('events');
const { Writable } = require('stream');
// ... moar

// Create the mixin mixer, we'll extend this. always.
const Mixin = (...args) => {
  // Parent class, this constant needs to return a constructor
  // so we'll have the constructor map all of our classes into it
  return class Mixin {
    constructor(){
      args.forEach(Class => Object.assign(this, Class.prototype));
    }
  };
}

// Usage ...
class NewClass extends Mixin(EventEmitter, Writable, ..., ...) {
  constructor() {
    super();
    // we now have the methods from EventEmitter and Writable.
  }
}