Object Composition

// Glass Factory
function glass(state) {
  var glasses = 6
  state.glassPosition = 'up'
  
  return {
    glass: {
      clean: function () {
        state.cleaned = true
        console.info('Glass cleaned')
      },
      up: function () {
        state.glassPosition = 'up'
        console.info('Glass up')
      },
      down: function () {
        state.glassPosition = 'down'
        console.info('Glass down')
      },
      add: function () {
        glasses += 1
        console.info('Glass added')
      },
      get: function () {
        console.info('Total glasses: ', glasses)
      }
    }  
  }
}

// Engine Factory
function engine(state) {
  return {
    engine: {
      start: function () {
        state.started = true
        console.info('Engine started')
      },
      stop: function () {
        state.started = false
        console.info('Engine stopped')
      }
    }
  }
}

// Car compositor
function car() {
  var state = {
    started: false,
    cleaned: false,
    glassPosition: null
  }
  return Object.assign(
    {},
    engine(state),
    glass(state) 
  )
} 

// Usage
var myCar = car();
myCar.engine.start();
myCar.glass.down();

// This is the easy way for Composition Factories
// Factories are closures that returns objects with public methods 
// But they save an internal state with vars & private methods 
Object.assign({}, obj1, obj2) // Clona o fusiona objetos