53 lines
1.6 KiB
JavaScript
53 lines
1.6 KiB
JavaScript
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import { Subscriber } from '../Subscriber';
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/**
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* Emits the given constant value on the output Observable every time the source
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* Observable emits a value.
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*
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* <span class="informal">Like {@link map}, but it maps every source value to
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* the same output value every time.</span>
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*
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* <img src="./img/mapTo.png" width="100%">
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*
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* Takes a constant `value` as argument, and emits that whenever the source
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* Observable emits a value. In other words, ignores the actual source value,
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* and simply uses the emission moment to know when to emit the given `value`.
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*
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* @example <caption>Map every click to the string 'Hi'</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var greetings = clicks.mapTo('Hi');
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* greetings.subscribe(x => console.log(x));
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*
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* @see {@link map}
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*
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* @param {any} value The value to map each source value to.
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* @return {Observable} An Observable that emits the given `value` every time
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* the source Observable emits something.
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* @method mapTo
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* @owner Observable
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*/
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export function mapTo(value) {
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return (source) => source.lift(new MapToOperator(value));
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}
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class MapToOperator {
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constructor(value) {
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this.value = value;
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}
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call(subscriber, source) {
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return source.subscribe(new MapToSubscriber(subscriber, this.value));
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class MapToSubscriber extends Subscriber {
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constructor(destination, value) {
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super(destination);
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this.value = value;
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}
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_next(x) {
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this.destination.next(this.value);
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}
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}
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//# sourceMappingURL=mapTo.js.map
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