Optimized sequential if/else pattern for Rx observables. (see generateObservableOptimized)

.ts

/// <reference path="typings/globals/es6-shim/index.d.ts" />`

import * as Rx from 'rxjs';

function generateObservable(...args) {
    return Rx.Observable.of({
        count: arguments.length > 1 ? 0 : 1
    });
}

//non-optimized variant
generateObservable('a', 'b', 'c', 'd').
    flatMap(
        x => {
            if(x.count == 0) return generateObservable('a', 'b', 'c').flatMap(
                y => {
                    if(y.count == 0) {
                        return generateObservable('a', 'b').flatMap(
                            z => {
                                if(z.count == 0) return generateObservable('a');

                                return Rx.Observable.of(z);
                            }

                        );
                    }

                    return Rx.Observable.of(y);
                }
            );

            return Rx.Observable.of(x);
        }
    ).
    subscribe(console.log);

//optimized variant. developed with Sereoga
function generateObservableOptimized(...args: Array<any>) {
    return generateObservable.apply(null, args).flatMap(x => {
        if (x.count == 0) {
            return generateObservableOptimized.apply(null, args.slice(0, args.length - 1));
        }

        return Rx.Observable.of(x);
    });
}

generateObservableOptimized('a', 'b', 'c').subscribe(console.log);