a small event dispatcher based on es6 Map/Set

dispatcher.js

const dispatcher = () => {
  const eventMap = new Map()
  const getHandlers = (name) => {
    if ( !handlers.has(name)) {
      handlers.set(name, new Set())
    }
    return eventMap.get(name) 
  }
  
  const on = ({name, fn}) => {
    const handlers = getHandlers(name)
    handlers.add(handler)
    return () => {
      handlers.delete(handler)
    }
  }
  const dispatch = ({name, payload}) => {
    getHandlers(name).forEach((handler) => handler(payload))
  }
  return { dispatch, on }
}