42 lines
1.2 KiB
TypeScript
42 lines
1.2 KiB
TypeScript
import { SchedulerLike, Observable, SchedulerAction, Subscriber, asyncScheduler } from 'rxjs';
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/**
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* Creates an Observable that emits sequential numbers after increasing intervals of time
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* starting with `startPeriod`, ending with `endPeriod` and incrementing by `step`.
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*/
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export const increasingInterval = (
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{ startPeriod = 0, endPeriod = 5000, step = 1000 },
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scheduler: SchedulerLike = asyncScheduler
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): Observable<number> => {
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return new Observable<number>((subscriber) => {
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const state: IntervalState = {
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subscriber,
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counter: 0,
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period: startPeriod,
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step,
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endPeriod,
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};
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subscriber.add(scheduler.schedule(dispatch, startPeriod, state));
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return subscriber;
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});
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};
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function dispatch(this: SchedulerAction<IntervalState>, state?: IntervalState) {
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if (!state) {
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return;
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}
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const { subscriber, counter, period, step, endPeriod } = state;
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subscriber.next(counter);
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const newPeriod = Math.min(period + step, endPeriod);
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this.schedule({ subscriber, counter: counter + 1, period: newPeriod, step, endPeriod }, newPeriod);
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}
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interface IntervalState {
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subscriber: Subscriber<number>;
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counter: number;
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period: number;
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endPeriod: number;
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step: number;
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}
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