I am working with an array of numbers, specifically [1, 2, 3], and utilizing an HTTP service that includes a function to load data objects based on a given number:
function get(id: number): Observable<object>Can anyone help me figure out how to map my original array of numbers to an array of objects while preserving the order of elements?
If you want to handle multiple HTTP requests sequentially with a delay, you can utilize the concatMap operator.
const Observable = Rx.Observable;
function simulateHttpRequests(i) {
return Observable.of(i).delay(500);
}
Observable.from([1, 2, 3])
.concatMap(i => simulateHttpRequests(i))
.subscribe(response => console.log(response));
This code mimics the behavior of making multiple delayed HTTP requests. By using the concatMap() operator, the Observables are processed in sequential order.
To see this in action, check out the live demo: https://jsbin.com/subuxo/edit?js,console
Special thanks to @martin for providing the perfect solution:
function generateRandomPromise(value) {
return new Promise(resolve => setTimeout(() => resolve(`Resolved Promise: ${value}`), Math.floor(Math.random() * 1000 + 1000));
}
const numbersQueue = Rx.Observable.of([1, 2, 3, 4, 5]);
const results = numbersQueue
.mergeMap(queueItem => Rx.Observable.forkJoin(...queueItem.map(generateRandomPromise)));
const subscription = result.subscribe(value => console.log(value));
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