1 | import { Observable } from '../Observable';
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2 | import { SchedulerLike } from '../types';
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3 | /**
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4 | * Creates an Observable that emits sequential numbers every specified
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5 | * interval of time, on a specified {@link SchedulerLike}.
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6 | *
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7 | * <span class="informal">Emits incremental numbers periodically in time.
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8 | * </span>
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9 | *
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10 | * ![](interval.png)
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11 | *
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12 | * `interval` returns an Observable that emits an infinite sequence of
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13 | * ascending integers, with a constant interval of time of your choosing
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14 | * between those emissions. The first emission is not sent immediately, but
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15 | * only after the first period has passed. By default, this operator uses the
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16 | * `async` {@link SchedulerLike} to provide a notion of time, but you may pass any
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17 | * {@link SchedulerLike} to it.
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18 | *
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19 | * ## Example
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20 | * Emits ascending numbers, one every second (1000ms) up to the number 3
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21 | * ```ts
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22 | * import { interval } from 'rxjs';
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23 | * import { take } from 'rxjs/operators';
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24 | *
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25 | * const numbers = interval(1000);
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26 | *
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27 | * const takeFourNumbers = numbers.pipe(take(4));
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28 | *
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29 | * takeFourNumbers.subscribe(x => console.log('Next: ', x));
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30 | *
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31 | * // Logs:
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32 | * // Next: 0
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33 | * // Next: 1
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34 | * // Next: 2
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35 | * // Next: 3
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36 | * ```
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37 | *
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38 | * @see {@link timer}
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39 | * @see {@link delay}
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40 | *
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41 | * @param {number} [period=0] The interval size in milliseconds (by default)
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42 | * or the time unit determined by the scheduler's clock.
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43 | * @param {SchedulerLike} [scheduler=async] The {@link SchedulerLike} to use for scheduling
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44 | * the emission of values, and providing a notion of "time".
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45 | * @return {Observable} An Observable that emits a sequential number each time
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46 | * interval.
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47 | * @static true
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48 | * @name interval
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49 | * @owner Observable
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50 | */
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51 | export declare function interval(period?: number, scheduler?: SchedulerLike): Observable<number>;
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