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54 lines
3.1 KiB
54 lines
3.1 KiB
"use strict"; |
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var observeOn_1 = require('../operators/observeOn'); |
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/** |
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* |
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* Re-emits all notifications from source Observable with specified scheduler. |
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* |
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* <span class="informal">Ensure a specific scheduler is used, from outside of an Observable.</span> |
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* |
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* `observeOn` is an operator that accepts a scheduler as a first parameter, which will be used to reschedule |
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* notifications emitted by the source Observable. It might be useful, if you do not have control over |
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* internal scheduler of a given Observable, but want to control when its values are emitted nevertheless. |
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* |
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* Returned Observable emits the same notifications (nexted values, complete and error events) as the source Observable, |
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* but rescheduled with provided scheduler. Note that this doesn't mean that source Observables internal |
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* scheduler will be replaced in any way. Original scheduler still will be used, but when the source Observable emits |
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* notification, it will be immediately scheduled again - this time with scheduler passed to `observeOn`. |
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* An anti-pattern would be calling `observeOn` on Observable that emits lots of values synchronously, to split |
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* that emissions into asynchronous chunks. For this to happen, scheduler would have to be passed into the source |
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* Observable directly (usually into the operator that creates it). `observeOn` simply delays notifications a |
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* little bit more, to ensure that they are emitted at expected moments. |
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* |
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* As a matter of fact, `observeOn` accepts second parameter, which specifies in milliseconds with what delay notifications |
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* will be emitted. The main difference between {@link delay} operator and `observeOn` is that `observeOn` |
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* will delay all notifications - including error notifications - while `delay` will pass through error |
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* from source Observable immediately when it is emitted. In general it is highly recommended to use `delay` operator |
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* for any kind of delaying of values in the stream, while using `observeOn` to specify which scheduler should be used |
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* for notification emissions in general. |
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* |
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* @example <caption>Ensure values in subscribe are called just before browser repaint.</caption> |
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* const intervals = Rx.Observable.interval(10); // Intervals are scheduled |
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* // with async scheduler by default... |
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* |
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* intervals |
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* .observeOn(Rx.Scheduler.animationFrame) // ...but we will observe on animationFrame |
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* .subscribe(val => { // scheduler to ensure smooth animation. |
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* someDiv.style.height = val + 'px'; |
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* }); |
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* |
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* @see {@link delay} |
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* |
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* @param {IScheduler} scheduler Scheduler that will be used to reschedule notifications from source Observable. |
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* @param {number} [delay] Number of milliseconds that states with what delay every notification should be rescheduled. |
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* @return {Observable<T>} Observable that emits the same notifications as the source Observable, |
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* but with provided scheduler. |
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* |
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* @method observeOn |
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* @owner Observable |
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*/ |
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function observeOn(scheduler, delay) { |
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if (delay === void 0) { delay = 0; } |
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return observeOn_1.observeOn(scheduler, delay)(this); |
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} |
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exports.observeOn = observeOn; |
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//# sourceMappingURL=observeOn.js.map
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