//emit immediately, then every 5s

const source = Rx.Observable.timer(0, 5000);

//switch to new inner observable when source emits, invoke project function and emit values

const example = source.switchMap(() => Rx.Observable.interval(2000), (outerValue, innerValue, outerIndex, innerIndex) => ({outerValue, innerValue, outerIndex, innerIndex}));

/*

    Output:

    {outerValue: 0, innerValue: 0, outerIndex: 0, innerIndex: 0}

    {outerValue: 0, innerValue: 1, outerIndex: 0, innerIndex: 1}

    {outerValue: 1, innerValue: 0, outerIndex: 1, innerIndex: 0}

    {outerValue: 1, innerValue: 1, outerIndex: 1, innerIndex: 1}

*/

const subscribe = example.subscribe(val => console.log(val));