ref-count-clone.js

function refCount(source) {
  let length = 0;
  const onNewSubscriber = () => {
    const onUnsubscribe = () => {
      length--;
      if(length === 0) {
        source.connect().unsubscribe();
      }
    };
    length++;
    if(length === 1) {
      source.connect();
    }
    return onUnsubscribe;
  };
  const obs = () => source;
  return Rx.Observable.using(onNewSubscriber, obs);
}

const source = Rx.Observable
  .interval(1000)
  .take(10)
  .publishReplay(1)
  .let(refCount);