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60 lines
2.7 KiB
60 lines
2.7 KiB
import { Observable, SubscribableOrPromise } from '../Observable'; |
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import { Subscriber } from '../Subscriber'; |
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import { Subscription } from '../Subscription'; |
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/** |
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* We need this JSDoc comment for affecting ESDoc. |
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* @extends {Ignored} |
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* @hide true |
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*/ |
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export declare class DeferObservable<T> extends Observable<T> { |
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private observableFactory; |
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/** |
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* Creates an Observable that, on subscribe, calls an Observable factory to |
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* make an Observable for each new Observer. |
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* |
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* <span class="informal">Creates the Observable lazily, that is, only when it |
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* is subscribed. |
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* </span> |
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* |
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* <img src="./img/defer.png" width="100%"> |
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* |
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* `defer` allows you to create the Observable only when the Observer |
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* subscribes, and create a fresh Observable for each Observer. It waits until |
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* an Observer subscribes to it, and then it generates an Observable, |
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* typically with an Observable factory function. It does this afresh for each |
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* subscriber, so although each subscriber may think it is subscribing to the |
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* same Observable, in fact each subscriber gets its own individual |
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* Observable. |
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* |
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* @example <caption>Subscribe to either an Observable of clicks or an Observable of interval, at random</caption> |
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* var clicksOrInterval = Rx.Observable.defer(function () { |
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* if (Math.random() > 0.5) { |
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* return Rx.Observable.fromEvent(document, 'click'); |
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* } else { |
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* return Rx.Observable.interval(1000); |
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* } |
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* }); |
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* clicksOrInterval.subscribe(x => console.log(x)); |
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* |
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* // Results in the following behavior: |
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* // If the result of Math.random() is greater than 0.5 it will listen |
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* // for clicks anywhere on the "document"; when document is clicked it |
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* // will log a MouseEvent object to the console. If the result is less |
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* // than 0.5 it will emit ascending numbers, one every second(1000ms). |
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* |
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* @see {@link create} |
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* |
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* @param {function(): SubscribableOrPromise} observableFactory The Observable |
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* factory function to invoke for each Observer that subscribes to the output |
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* Observable. May also return a Promise, which will be converted on the fly |
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* to an Observable. |
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* @return {Observable} An Observable whose Observers' subscriptions trigger |
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* an invocation of the given Observable factory function. |
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* @static true |
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* @name defer |
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* @owner Observable |
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*/ |
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static create<T>(observableFactory: () => SubscribableOrPromise<T> | void): Observable<T>; |
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constructor(observableFactory: () => SubscribableOrPromise<T> | void); |
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/** @deprecated internal use only */ _subscribe(subscriber: Subscriber<T>): Subscription; |
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}
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