github-pages-deploy-action/node_modules/rxjs/internal/operators/mapTo.d.ts

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2020-03-07 11:45:40 +08:00
import { OperatorFunction } from '../types';
/**
* Emits the given constant value on the output Observable every time the source
* Observable emits a value.
*
* <span class="informal">Like {@link map}, but it maps every source value to
* the same output value every time.</span>
*
* ![](mapTo.png)
*
* Takes a constant `value` as argument, and emits that whenever the source
* Observable emits a value. In other words, ignores the actual source value,
* and simply uses the emission moment to know when to emit the given `value`.
*
* ## Example
* Map every click to the string 'Hi'
* ```ts
* import { fromEvent } from 'rxjs';
* import { mapTo } from 'rxjs/operators';
*
* const clicks = fromEvent(document, 'click');
* const greetings = clicks.pipe(mapTo('Hi'));
* greetings.subscribe(x => console.log(x));
* ```
*
* @see {@link map}
*
* @param {any} value The value to map each source value to.
* @return {Observable} An Observable that emits the given `value` every time
* the source Observable emits something.
* @method mapTo
* @owner Observable
*/
export declare function mapTo<T, R>(value: R): OperatorFunction<T, R>;