import { Operator } from '../Operator'; import { Subscriber } from '../Subscriber'; import { Notification } from '../Notification'; import { MonoTypeOperatorFunction, PartialObserver, SchedulerAction, SchedulerLike, TeardownLogic } from '../types'; /** * * Re-emits all notifications from source Observable with specified scheduler. * * Ensure a specific scheduler is used, from outside of an Observable. * * `observeOn` is an operator that accepts a scheduler as a first parameter, which will be used to reschedule * notifications emitted by the source Observable. It might be useful, if you do not have control over * internal scheduler of a given Observable, but want to control when its values are emitted nevertheless. * * Returned Observable emits the same notifications (nexted values, complete and error events) as the source Observable, * but rescheduled with provided scheduler. Note that this doesn't mean that source Observables internal * scheduler will be replaced in any way. Original scheduler still will be used, but when the source Observable emits * notification, it will be immediately scheduled again - this time with scheduler passed to `observeOn`. * An anti-pattern would be calling `observeOn` on Observable that emits lots of values synchronously, to split * that emissions into asynchronous chunks. For this to happen, scheduler would have to be passed into the source * Observable directly (usually into the operator that creates it). `observeOn` simply delays notifications a * little bit more, to ensure that they are emitted at expected moments. * * As a matter of fact, `observeOn` accepts second parameter, which specifies in milliseconds with what delay notifications * will be emitted. The main difference between {@link delay} operator and `observeOn` is that `observeOn` * will delay all notifications - including error notifications - while `delay` will pass through error * from source Observable immediately when it is emitted. In general it is highly recommended to use `delay` operator * for any kind of delaying of values in the stream, while using `observeOn` to specify which scheduler should be used * for notification emissions in general. * * ## Example * Ensure values in subscribe are called just before browser repaint. * ```javascript * const intervals = interval(10); // Intervals are scheduled * // with async scheduler by default... * intervals.pipe( * observeOn(animationFrameScheduler), // ...but we will observe on animationFrame * ) // scheduler to ensure smooth animation. * .subscribe(val => { * someDiv.style.height = val + 'px'; * }); * ``` * * @see {@link delay} * * @param {SchedulerLike} scheduler Scheduler that will be used to reschedule notifications from source Observable. * @param {number} [delay] Number of milliseconds that states with what delay every notification should be rescheduled. * @return {Observable} Observable that emits the same notifications as the source Observable, * but with provided scheduler. * * @method observeOn * @owner Observable */ export declare function observeOn(scheduler: SchedulerLike, delay?: number): MonoTypeOperatorFunction; export declare class ObserveOnOperator implements Operator { private scheduler; private delay; constructor(scheduler: SchedulerLike, delay?: number); call(subscriber: Subscriber, source: any): TeardownLogic; } /** * We need this JSDoc comment for affecting ESDoc. * @ignore * @extends {Ignored} */ export declare class ObserveOnSubscriber extends Subscriber { private scheduler; private delay; /** @nocollapse */ static dispatch(this: SchedulerAction, arg: ObserveOnMessage): void; constructor(destination: Subscriber, scheduler: SchedulerLike, delay?: number); private scheduleMessage; protected _next(value: T): void; protected _error(err: any): void; protected _complete(): void; } export declare class ObserveOnMessage { notification: Notification; destination: PartialObserver; constructor(notification: Notification, destination: PartialObserver); }