pausablebuffered.js

  function combineLatestSource(source, subject, resultSelector) {
    return new AnonymousObservable(function (o) {
      var hasValue = [false, false],
        hasValueAll = false,
        isDone = false,
        values = new Array(2),
        err;

      function next(x, i) {
        values[i] = x;
        hasValue[i] = true;
        if (hasValueAll || (hasValueAll = hasValue.every(identity))) {
          if (err) { return o.onError(err); }
          var res = tryCatch(resultSelector).apply(null, values);
          if (res === errorObj) { return o.onError(res.e); }
          o.onNext(res);
        }
        isDone && values[1] && o.onCompleted();
      }

      return new BinaryDisposable(
        source.subscribe(
          function (x) {
            next(x, 0);
          },
          function (e) {
            if (values[1]) {
              o.onError(e);
            } else {
              err = e;
            }
          },
          function () {
            isDone = true;
            values[1] && o.onCompleted();
          }),
        subject.subscribe(
          function (x) {
            next(x, 1);
          },
          function (e) { o.onError(e); },
          function () {
            isDone = true;
            next(true, 1);
          })
        );
    }, source);
  }

  var PausableBufferedObservable = (function (__super__) {
    inherits(PausableBufferedObservable, __super__);
    function PausableBufferedObservable(source, pauser) {
      this.source = source;
      this.controller = new Subject();
      this.paused = true;

      if (pauser && pauser.subscribe) {
        this.pauser = this.controller.merge(pauser);
      } else {
        this.pauser = this.controller;
      }

      __super__.call(this);
    }

    PausableBufferedObservable.prototype._subscribe = function (o) {
      var q = [], previousShouldFire;

      function drainQueue() { while (q.length > 0) { o.onNext(q.shift()); } }

      var subscription =
        combineLatestSource(
          this.source,
          this.pauser.startWith(!this.paused).distinctUntilChanged(),
          function (data, shouldFire) {
            return { data: data, shouldFire: shouldFire };
          })
          .subscribe(
            function (results) {
              if (previousShouldFire !== undefined && results.shouldFire !== previousShouldFire) {
                previousShouldFire = results.shouldFire;
                // change in shouldFire
                if (results.shouldFire) { drainQueue(); }
              } else {
                previousShouldFire = results.shouldFire;
                // new data
                if (results.shouldFire) {
                  o.onNext(results.data);
                } else {
                  q.push(results.data);
                }
              }
            },
            function (err) {
              drainQueue();
              o.onError(err);
            },
            function () {
              drainQueue();
              o.onCompleted();
            }
          );
      return subscription;      
    };

    PausableBufferedObservable.prototype.pause = function () {
      this.paused = true;
      this.controller.onNext(false);
    };

    PausableBufferedObservable.prototype.resume = function () {
      this.paused = false;
      this.controller.onNext(true);
    };

    return PausableBufferedObservable;

  }(Observable));

  /**
   * Pauses the underlying observable sequence based upon the observable sequence which yields true/false,
   * and yields the values that were buffered while paused.
   * @example
   * var pauser = new Rx.Subject();
   * var source = Rx.Observable.interval(100).pausableBuffered(pauser);
   * @param {Observable} pauser The observable sequence used to pause the underlying sequence.
   * @returns {Observable} The observable sequence which is paused based upon the pauser.
   */
  observableProto.pausableBuffered = function (pauser) {
    return new PausableBufferedObservable(this, pauser);
  };