slice.js

  var SliceObservable = (function (__super__) {
    inherits(SliceObservable, __super__);
    function SliceObservable(source, b, e) {
      this.source = source;
      this._b = b;
      this._e = e;
      __super__.call(this);
    }

    SliceObservable.prototype.subscribeCore = function (o) {
      return this.source.subscribe(new SliceObserver(o, this._b, this._e));
    };

    return SliceObservable;
  }(ObservableBase));

  var SliceObserver = (function (__super__) {
    inherits(SliceObserver, __super__);

    function SliceObserver(o, b, e) {
      this._o = o;
      this._b = b;
      this._e = e;
      this._i = 0;
      __super__.call(this);
    }

    SliceObserver.prototype.next = function (x) {
      if (this._i >= this._b) {
        if (this._e === this._i) {
          this._o.onCompleted();
        } else {
          this._o.onNext(x);
        }
      }
      this._i++;
    };
    SliceObserver.prototype.error = function (e) { this._o.onError(e); };
    SliceObserver.prototype.completed = function () { this._o.onCompleted(); };

    return SliceObserver;
  }(AbstractObserver));

  /*
  * The slice() method returns a shallow copy of a portion of an Observable into a new Observable object.
  * Unlike the array version, this does not support negative numbers for being or end.
  * @param {Number} [begin] Zero-based index at which to begin extraction. If omitted, this will default to zero.
  * @param {Number} [end] Zero-based index at which to end extraction. slice extracts up to but not including end.
  * If omitted, this will emit the rest of the Observable object.
  * @returns {Observable} A shallow copy of a portion of an Observable into a new Observable object.
  */
  observableProto.slice = function (begin, end) {
    var start = begin || 0;
    if (start < 0) { throw new Rx.ArgumentOutOfRangeError(); }
    if (typeof end === 'number' && end < start) {
      throw new Rx.ArgumentOutOfRangeError();
    }
    return new SliceObservable(this, start, end);
  };