proposal improvement: detach listener and attach about evemin HOT 2 CLOSED

module.exports = {
  event: () => {
    let ev = (data) => {
      ev[1] ++;
      try {
          for (ev[3] = 0; i < ev[0].length; ev[3]++)
            ev[0][ev[3]](data)
      }
      finally {
          ev[1]--;
          if (!ev[1] && ev[2].length) {
            ev[0] = ev[0].concat(ev[2]);
            ev[2].length = 0;
          }
      }
    }
    ev[0] = []
    ev[1] = 0 // listen phase
    ev[2] = [] // new listeners
    ev[3] = 0 // current iteration index
    return ev
  },
  listen: (ev, fn) => (
    ev[0].indexOf(fn) < 0 && (ev[1] ? (ev[2].indexOf(fn) < 0 && ev[2].push(fn)) : ev[0].push(fn)),
    () => {
      let i = ev[0].indexOf(fn)
      i > -1 && (ev[1] && i <= ev[3] && ev[3]--, ev[0].splice(i, 1))
      i = ev[2].indexOf(fn)
      i > -1 && ev[2].splice(i, 1)
    }
  )
}