AsyncStorageObservableWithLeak.js

function buttonClicked() {
    var buttonClickedStream = Rx.Observable.just(null);
    
    buttonClickedStream
        .flatMap(getDataFromStorage)
        .filter(checkIfdataMoreThanADayOld)
        .flatMap(getNewData)
        .map(performComplexOperations)
        .subscribe((combinedData) => {
            console.log(combinedData);
        },
        (error) => {
            console.log('An error occured');
        });
}

function getDataFromStorage() {
    var dataStream1 = Rx.Observable.fromPromise(AsyncStorage.getItem(KEY_1));
    var dataStream2 = Rx.Observable.fromPromise(AsyncStorage.getItem(KEY_2));
    var dataStream3 = Rx.Observable.fromPromise(AsyncStorage.getItem(KEY_3));
    
    return dataStream1
            .combineLatest(
                dataStream2,
                dataStream3,
                (data1, data2, data3) => {
                    return {
                        data1: data1,
                        data2: data2, 
                        data3: data3
                    };
                });
}

function checkIfdataMoreThanADayOld(combinedData) {
    return combinedData.moreThanADayOld();
}

function getNewData(combinedData) {
    var newDataStream = Rx.Observable.fromPromise(fetch('www.example.com/newData'));
    var oldDataStream = Rx.Observable.just(combinedData);
    
    return newDataStream
            .combineLatest(
                oldDataStream,
                (newData, oldData) => {
                    return {
                        newData: newData,
                        oldData: oldData
                    };
                });
}

function performComplexOperations(combineApiAndLocalData) {
    //Perform complex operations with combineApiAndLocalData
    //...
    //...
    //More opeations
    return 'Successfully updated old data';
}