1.js

Runtime.prototype.observe = function(queries, cb) {
  var self = this;
  var filters = [];

  queries.forEach(function(query){
    var filter = self._observable.filter(function(device) {
      return query.match(device);
    });
    filters.push(filter);
  });

  var source = null;
  if(filters.length > 1) {
    filters.push(function() {
      return Array.prototype.slice.call(arguments);
    });
    source = Rx.Observable.zip.apply(null, filters);
  } else {
    source = filters[0];
  }

  
  if(this._jsDevices.length){
    var alreadyDiscoveredSource = Rx.Observable.create(function(observer){
      Object.keys(self._jsDevices).forEach(function(device){
        observer.onNext(self._jsDevices[device]);
      });
      observer.onCompleted();
    });
    
    this._observable.merge(alreadyDiscoveredSource);
  }

  source
    .subscribe(function(args){
      if (Array.isArray(args)) {
        cb.apply(null, args);
      } else {
        cb.apply(null, [args]);
      }
    });
};