39 lines
1.5 KiB
JavaScript
39 lines
1.5 KiB
JavaScript
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import { find as higherOrder } from '../operators/find';
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/* tslint:enable:max-line-length */
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/**
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* Emits only the first value emitted by the source Observable that meets some
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* condition.
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*
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* <span class="informal">Finds the first value that passes some test and emits
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* that.</span>
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*
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* <img src="./img/find.png" width="100%">
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*
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* `find` searches for the first item in the source Observable that matches the
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* specified condition embodied by the `predicate`, and returns the first
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* occurrence in the source. Unlike {@link first}, the `predicate` is required
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* in `find`, and does not emit an error if a valid value is not found.
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*
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* @example <caption>Find and emit the first click that happens on a DIV element</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var result = clicks.find(ev => ev.target.tagName === 'DIV');
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* result.subscribe(x => console.log(x));
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*
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* @see {@link filter}
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* @see {@link first}
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* @see {@link findIndex}
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* @see {@link take}
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*
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* @param {function(value: T, index: number, source: Observable<T>): boolean} predicate
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* A function called with each item to test for condition matching.
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* @param {any} [thisArg] An optional argument to determine the value of `this`
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* in the `predicate` function.
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* @return {Observable<T>} An Observable of the first item that matches the
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* condition.
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* @method find
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* @owner Observable
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*/
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export function find(predicate, thisArg) {
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return higherOrder(predicate, thisArg)(this);
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}
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//# sourceMappingURL=find.js.map
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