/* Have staggering intervals */

var source1 = Rx.Observable.interval(100)

    .map(i => `First: ${i}`);

​

var source2 = Rx.Observable.interval(150)

    .map(i => `Second: ${i}`);

​

// Combine latest of source1 and source2 whenever either gives a value

var source = Rx.Observable.combineLatest(

        source1,

        source2

    ).take(4);

​

var subscription = source.subscribe(

  x => console.log(`onNext: ${x}`),

  e => console.log(`onError: ${e}`),

  () => console.log('onCompleted'));

​

// => onNext: First: 0, Second: 0

// => onNext: First: 1, Second: 0

// => onNext: First: 1, Second: 1

// => onNext: First: 2, Second: 1

// => onCompleted