console.clear();

​

Rx.Observable.prototype.handleFn = function (fn) {

​

    const source = this;

​

    return Rx.Observable.create(function (obs) {

​

        return source.subscribe(function(val){

            obs.next(fn.call(obs,val));

        });

    });

​

};

​

const obs = Rx.Observable.interval(1000)

    .handleFn(function(){

        return Rx.Observable.timer(150).mapTo(Math.random());

    })

    .mergeAll();

​

obs.subscribe(x => console.log(x))