``Infinite loops in rxjs: how to create a never-ending task

Question

``Infinite loops in rxjs: how to create a never-ending task

I'm working on a never-ending task that needs to loop continuously in TypeScript.

The next task should only start when the previous one has finished.

I've decided to utilize rxjs for this because it appears to be the most concise approach.

My attempts with interval, queue scheduler, defer, exhaust, and exhaust map haven't been very successful so far.

This is my current code snippet:

function longTask(): void {
    // some lengthy process
}

interval(1000)
.pipe(
     exhaustMap((x) => 
         defer(()=> longTask())
     )
.subscribe();

Any assistance would be greatly appreciated.

typescript rxjs

Answer 1

Answer №1

Utilize the zip function, which will trigger the interval and then pause for your observable to be triggered.

zip(interval(1000), longTask()).subscribe(([_, longTaskResult]) => {
});

Alternatively, if your longTask only emits once and completes, you could implement a recursive call

const { of } = rxjs;
const { delay } = rxjs.operators;

const longTask = () => of(Math.random() * 10).pipe(delay(Math.floor(Math.random() * 5000)));

const runLongTask = () => {
  longTask().subscribe(result => {
    console.log(result);
    runLongTask();
  });
}

runLongTask();

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/6.5.3/rxjs.umd.min.js"></script>

Answer 2

Utilize the zip function, which will trigger the interval and then pause for your observable to be triggered.

zip(interval(1000), longTask()).subscribe(([_, longTaskResult]) => {
});

Alternatively, if your longTask only emits once and completes, you could implement a recursive call

const { of } = rxjs;
const { delay } = rxjs.operators;

const longTask = () => of(Math.random() * 10).pipe(delay(Math.floor(Math.random() * 5000)));

const runLongTask = () => {
  longTask().subscribe(result => {
    console.log(result);
    runLongTask();
  });
}

runLongTask();

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/6.5.3/rxjs.umd.min.js"></script>

``Infinite loops in rxjs: how to create a never-ending task

Answer №1

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