📢 Dead simple tweetable JavaScript Emitter pattern module using Map (ES2015)

1-info.md

See also 📰 Dead simple tweetable JavaScript PubSub pattern module using Set (ES2015) which this package uses.

Browser compatibility

Chrome*	Edge	FF	IE	Opera	Safari	iOS
38	12	13	-*	25	7.1	8

Notes:

• Chrome includes mobile Chrome.
• IE 11 does not support only arrow functions, they can be replaced with function. See, pubsub for more compatibility info of that package.

emitter.js

import pubsub from './pubsub'
// Import the dead simple tweetable JavaScript PubSub pattern module using Set (ES2015)
// See https://gist.github.com/robinpokorny/d743ed9e0bc5214f79076a16c8e44a8f

export default () => {
  const events = new Map()
  
  const on = (name, fn) => {
    if (!events.has(name)) events.set(name, pubsub())

    return events.get(name).sub(fn)
  }
  
  const emit = (name, data) => events.has(name) && events.get(name).pub(data)
  
  return Object.freeze({ on, emit })
}

emitter.min.js

import p from './pubsub'
// Minified (by hand), 139 bytes
export default e=>(e=new Map, Object.freeze({on:(n,f)=>(e.has(name)||e.set(n,p()),e.get(n).sub(f)),emit:(n,d)=>e.has(n)&&e.get(n).pub(d)}))