Tiny implementation of PubSub

tinypubsub.js

let ps = (function(){
  let events = {}
  
  let on = (eventName,cb) => {
    events[eventName] = (events[eventName] || []).concat(cb);
    return () => events[eventName] = events[eventName].filter(each => each !== cb );
  }
  
  let pub = (eventName, data) => {
    (events[eventName] || []).forEach(cb => cb(data));
  }
  
  return {pub,on};
})()

/** Run in console
let handler1 = ps.on('asd',(data)=> console.log(`I am sub 1 - You passed ${data}`))
let handler2 = ps.on('new',(data)=> console.log(`I am sub 2 - You passed ${data}`))

ps.pub('asd','asd')
ps.pub('new','new')

console.log('unsubscribing handler for event: asd');
handler1(); // <= Unsubscribing
ps.pub('asd','asd')
ps.pub('new','asd')
*/

Uglified version fits in a tweet!

let ps=function(){let t={};return{pub:(n,c)=>{(t[n]||[]).forEach(t=>t(c))},on:(n,c)=>(t[n]=(t[n]||[]).concat(c),()=>t[n]=t[n].filter(t=>t!==c))}}();