Right now the spec has example
socket.onopen = function () {
    setInterval(function() {
      if (socket.bufferedAmount == 0)
        socket.send(getUpdateData());
    }, 50);
  };

That works, sure, but in many cases there shouldn't be a need for such interval.
Especially in worker context something like:
socket.onemptybuffer = function () {
    socket.send(getUpdateData());
  };
could work quite nicely.