Using Generators with Rx.Observable.from:

rx-example.js

function* fibonacci(){
  var fn1 = 1;
  var fn2 = 1;
  while (1){
    var current = fn2;
    fn2 = fn1;
    fn1 = fn1 + current;
    yield current;
  }
}

Rx.Observable.from(fibonacci())
  .take(10)
  .subscribe(function (x) {
    console.log('Value: %s', x);
  });
  
//=> Value: 1
//=> Value: 1
//=> Value: 2
//=> Value: 3
//=> Value: 5
//=> Value: 8
//=> Value: 13
//=> Value: 21
//=> Value: 34
//=> Value: 55

checkout naman34/grunge for something similar without Rx.