36 lines
1.6 KiB
TypeScript
36 lines
1.6 KiB
TypeScript
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import { Observable } from '../Observable';
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/**
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* Applies a given `project` function to each value emitted by the source
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* Observable, and emits the resulting values as an Observable.
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*
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* <span class="informal">Like [Array.prototype.map()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map),
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* it passes each source value through a transformation function to get
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* corresponding output values.</span>
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*
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* <img src="./img/map.png" width="100%">
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*
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* Similar to the well known `Array.prototype.map` function, this operator
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* applies a projection to each value and emits that projection in the output
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* Observable.
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*
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* @example <caption>Map every click to the clientX position of that click</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var positions = clicks.map(ev => ev.clientX);
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* positions.subscribe(x => console.log(x));
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*
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* @see {@link mapTo}
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* @see {@link pluck}
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*
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* @param {function(value: T, index: number): R} project The function to apply
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* to each `value` emitted by the source Observable. The `index` parameter is
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* the number `i` for the i-th emission that has happened since the
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* subscription, starting from the number `0`.
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* @param {any} [thisArg] An optional argument to define what `this` is in the
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* `project` function.
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* @return {Observable<R>} An Observable that emits the values from the source
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* Observable transformed by the given `project` function.
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* @method map
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* @owner Observable
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*/
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export declare function map<T, R>(this: Observable<T>, project: (value: T, index: number) => R, thisArg?: any): Observable<R>;
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