const Observable = Rx.Observable;

​

var counter = 1;

var updateRequest = Observable.defer(() => makeMockHttpRequest())

    .publishReplay(1, 1000)

    .refCount()

    .take(1);

​

function makeMockHttpRequest() {

    return Observable.of(counter++)

        .delay(100)

        .map(i => {

            if (i === 2) {

                throw new Error('Invalid URL');

            }

            return i;

        })

        .catch(err => Observable.of(err));

}

​

function requestCachedHttpResult() {

    return updateRequest;

}

​

requestCachedHttpResult().subscribe(val => console.log("Response 0:", val));

​

setTimeout(() => requestCachedHttpResult()

    .subscribe(val => console.log("Response 50:", val))

, 50);

​

setTimeout(() => requestCachedHttpResult()

    .subscribe(val => console.log("Response 200:", val))

, 200);

​

setTimeout(() => requestCachedHttpResult()

    .subscribe(val => console.log("Response 1200:", val))

, 1200);

​

setTimeout(() => requestCachedHttpResult()

    .subscribe(val => console.log("Response 1500:", val))

, 1500);

​

setTimeout(() => requestCachedHttpResult()

    .subscribe(val => console.log("Response 3500:", val))

, 3500);

​