1 import { Observable } from '../Observable';
2 import { SchedulerAction, SchedulerLike } from '../types';
3 import { async } from '../scheduler/async';
4 import { isNumeric } from '../util/isNumeric';
5 import { isScheduler } from '../util/isScheduler';
6 import { Subscriber } from '../Subscriber';
9 * Creates an Observable that starts emitting after an `dueTime` and
10 * emits ever increasing numbers after each `period` of time thereafter.
12 * <span class="informal">Its like {@link index/interval}, but you can specify when
13 * should the emissions start.</span>
17 * `timer` returns an Observable that emits an infinite sequence of ascending
18 * integers, with a constant interval of time, `period` of your choosing
19 * between those emissions. The first emission happens after the specified
20 * `dueTime`. The initial delay may be a `Date`. By default, this
21 * operator uses the {@link asyncScheduler} {@link SchedulerLike} to provide a notion of time, but you
22 * may pass any {@link SchedulerLike} to it. If `period` is not specified, the output
23 * Observable emits only one value, `0`. Otherwise, it emits an infinite
27 * ### Emits ascending numbers, one every second (1000ms), starting after 3 seconds
29 * import { timer } from 'rxjs';
31 * const numbers = timer(3000, 1000);
32 * numbers.subscribe(x => console.log(x));
35 * ### Emits one number after five seconds
37 * import { timer } from 'rxjs';
39 * const numbers = timer(5000);
40 * numbers.subscribe(x => console.log(x));
42 * @see {@link index/interval}
45 * @param {number|Date} [dueTime] The initial delay time specified as a Date object or as an integer denoting
46 * milliseconds to wait before emitting the first value of 0`.
47 * @param {number|SchedulerLike} [periodOrScheduler] The period of time between emissions of the
49 * @param {SchedulerLike} [scheduler=async] The {@link SchedulerLike} to use for scheduling
50 * the emission of values, and providing a notion of "time".
51 * @return {Observable} An Observable that emits a `0` after the
52 * `dueTime` and ever increasing numbers after each `period` of time
58 export function timer(dueTime: number | Date = 0,
59 periodOrScheduler?: number | SchedulerLike,
60 scheduler?: SchedulerLike): Observable<number> {
62 if (isNumeric(periodOrScheduler)) {
63 period = Number(periodOrScheduler) < 1 && 1 || Number(periodOrScheduler);
64 } else if (isScheduler(periodOrScheduler)) {
65 scheduler = periodOrScheduler as any;
68 if (!isScheduler(scheduler)) {
72 return new Observable(subscriber => {
73 const due = isNumeric(dueTime)
75 : (+dueTime - scheduler.now());
77 return scheduler.schedule(dispatch, due, {
78 index: 0, period, subscriber
83 interface TimerState {
86 subscriber: Subscriber<number>;
89 function dispatch(this: SchedulerAction<TimerState>, state: TimerState) {
90 const { index, period, subscriber } = state;
91 subscriber.next(index);
93 if (subscriber.closed) {
95 } else if (period === -1) {
96 return subscriber.complete();
99 state.index = index + 1;
100 this.schedule(state, period);