Bacon.js control buffering of stream with other stream

Question

I want to buffer values of an EventStream in Bacon.js exactly like buffer(closingSelector) behaves in RxJava. When the "controller stream" (closingSelector in RxJava method) emits a new value, then the event buffer gets flushed.

So I want that the stream output is similar as in stream.bufferWithTimeOrCount, but instead of controlling buffering with time interval or event count I want to control buffering with other stream.

Is there an easy way to implement this in Bacon.js?

Answer 1

Bacon.js didn't have the function as you needed it, so I looked at the bacon.js source and wrote a modified version of holdWhen.

Bacon.EventStream.prototype.bufferUntilValue = function(valve) {
var valve_ = valve.startWith(false);

  return this.filter(false).merge(valve_.flatMapConcat((function(_this) {
    return function() {
        return _this.scan([], (function(xs, x) {
            return xs.concat(x);
        }), {
            eager: true
        }).sampledBy(valve).take(1);
    };
  })(this)));
};

To see this in action, check out this jsFiddle.