const pubSub = () => {
  const handlers = {}

  const dispatch = (event, data) => {
    if(handlers[eventName]) {
      handlers[eventName].forEach(h => h(data))
    }
   }

   const on = (eventName, handler) => {
    if (!handlers[eventName]) handlers[eventName] = []
    handlers[eventName].push(handler)
  }

  const off = (eventName, handler) => {
    if(handlers[eventName]){
      handlers[eventName] = handlers[eventName].filter(h => h!== handler)
    }
    
  }


  return {
    on, off, handlers, dispatch
  },
}


const someThing = () => {
  const {handlers, on, off, dispatch} = pubSub()
  
  const getData = () => {
    console.log('getting data')
    dispatch('data.ready', data)
  }
  
  const othertData = () => {
    console.log('getting other data')
    dispatch('other.data.ready', data)
  }
  
  return {on, off, otherData}
}

const something = someThing()
something.on('data.ready', ()=>{
   ...
}}

something.getData();