Exponential backoff with RxJs (modified sample code from docs)

rx-retry-backoff.js

var Rx = require('rx')
var MAX_RETRIES = 4

Rx.Observable.throw(new Error("always fails"))
  .retryWhen(function (errors) {
      return Rx.Observable.zip(
        Rx.Observable.range(1, MAX_RETRIES), errors, function (i, e) { return i })
        .flatMap(function (i) {
          console.log("delay retry by " + i + " second(s)");
          return Rx.Observable.timer(i * 1000);
      });
  }).subscribe();

Nice, but what happens when the maximum amount of retries is reached? I don't think onError is called in this case, while I think it should be.