1 | import { Operator } from '../Operator';
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2 | import { Subscriber } from '../Subscriber';
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3 | import { Notification } from '../Notification';
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4 | import { MonoTypeOperatorFunction, PartialObserver, SchedulerAction, SchedulerLike, TeardownLogic } from '../types';
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5 | /**
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6 | *
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7 | * Re-emits all notifications from source Observable with specified scheduler.
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8 | *
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9 | * <span class="informal">Ensure a specific scheduler is used, from outside of an Observable.</span>
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10 | *
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11 | * `observeOn` is an operator that accepts a scheduler as a first parameter, which will be used to reschedule
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12 | * notifications emitted by the source Observable. It might be useful, if you do not have control over
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13 | * internal scheduler of a given Observable, but want to control when its values are emitted nevertheless.
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14 | *
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15 | * Returned Observable emits the same notifications (nexted values, complete and error events) as the source Observable,
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16 | * but rescheduled with provided scheduler. Note that this doesn't mean that source Observables internal
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17 | * scheduler will be replaced in any way. Original scheduler still will be used, but when the source Observable emits
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18 | * notification, it will be immediately scheduled again - this time with scheduler passed to `observeOn`.
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19 | * An anti-pattern would be calling `observeOn` on Observable that emits lots of values synchronously, to split
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20 | * that emissions into asynchronous chunks. For this to happen, scheduler would have to be passed into the source
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21 | * Observable directly (usually into the operator that creates it). `observeOn` simply delays notifications a
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22 | * little bit more, to ensure that they are emitted at expected moments.
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23 | *
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24 | * As a matter of fact, `observeOn` accepts second parameter, which specifies in milliseconds with what delay notifications
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25 | * will be emitted. The main difference between {@link delay} operator and `observeOn` is that `observeOn`
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26 | * will delay all notifications - including error notifications - while `delay` will pass through error
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27 | * from source Observable immediately when it is emitted. In general it is highly recommended to use `delay` operator
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28 | * for any kind of delaying of values in the stream, while using `observeOn` to specify which scheduler should be used
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29 | * for notification emissions in general.
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30 | *
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31 | * ## Example
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32 | * Ensure values in subscribe are called just before browser repaint.
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33 | * ```ts
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34 | * import { interval } from 'rxjs';
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35 | * import { observeOn } from 'rxjs/operators';
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36 | *
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37 | * const intervals = interval(10); // Intervals are scheduled
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38 | * // with async scheduler by default...
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39 | * intervals.pipe(
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40 | * observeOn(animationFrameScheduler), // ...but we will observe on animationFrame
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41 | * ) // scheduler to ensure smooth animation.
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42 | * .subscribe(val => {
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43 | * someDiv.style.height = val + 'px';
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44 | * });
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45 | * ```
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46 | *
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47 | * @see {@link delay}
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48 | *
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49 | * @param {SchedulerLike} scheduler Scheduler that will be used to reschedule notifications from source Observable.
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50 | * @param {number} [delay] Number of milliseconds that states with what delay every notification should be rescheduled.
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51 | * @return {Observable<T>} Observable that emits the same notifications as the source Observable,
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52 | * but with provided scheduler.
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53 | *
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54 | * @method observeOn
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55 | * @owner Observable
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56 | */
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57 | export declare function observeOn<T>(scheduler: SchedulerLike, delay?: number): MonoTypeOperatorFunction<T>;
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58 | export declare class ObserveOnOperator<T> implements Operator<T, T> {
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59 | private scheduler;
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60 | private delay;
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61 | constructor(scheduler: SchedulerLike, delay?: number);
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62 | call(subscriber: Subscriber<T>, source: any): TeardownLogic;
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63 | }
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64 | /**
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65 | * We need this JSDoc comment for affecting ESDoc.
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66 | * @ignore
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67 | * @extends {Ignored}
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68 | */
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69 | export declare class ObserveOnSubscriber<T> extends Subscriber<T> {
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70 | private scheduler;
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71 | private delay;
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72 | /** @nocollapse */
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73 | static dispatch(this: SchedulerAction<ObserveOnMessage>, arg: ObserveOnMessage): void;
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74 | constructor(destination: Subscriber<T>, scheduler: SchedulerLike, delay?: number);
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75 | private scheduleMessage;
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76 | protected _next(value: T): void;
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77 | protected _error(err: any): void;
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78 | protected _complete(): void;
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79 | }
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80 | export declare class ObserveOnMessage {
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81 | notification: Notification<any>;
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82 | destination: PartialObserver<any>;
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83 | constructor(notification: Notification<any>, destination: PartialObserver<any>);
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84 | }
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