kidney-stone/public/index.js

let socket = io()
let ourId;
socket.on('gamers', gamers => { 
    gamersUL.innerHTML = '';
    for (let [id,gamer] of Object.entries(gamers)){
        let el = document.createElement('li')
        el.innerHTML = gamer.ready && id != ourId ? `<button>${gamer.nick}</button>` : gamer.nick;
        el.children[0] && (el.children[0].onclick = () => socket.emit('start', {with: id}))
        gamersUL.appendChild(el)
    }
})
socket.on('id', i => ourId = i)

const sendUpdate = ()=> socket.emit('hi', {nick: nick.value, ready: ready.checked})

hi.onclick = sendUpdate

ready.onchange = sendUpdate