Naive pub/sub

pubsub.ts

function Subscription() {
  const subs: Array<() => void> = [];

  return {
    subscribe(cb: () => void) {
      subs.push(cb);
      // return unsub
      return () => {
        const index = subs.indexOf(cb);
        subs.splice(index, 1);
      }
    },
    emit() {
      subs.forEach((cb) => {
        cb();
      })
    }
  }
}