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41 lines
1.6 KiB
41 lines
1.6 KiB
"use strict"; |
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var find_1 = require('../operators/find'); |
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/** |
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* Emits only the index of the first value emitted by the source Observable that |
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* meets some condition. |
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* |
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* <span class="informal">It's like {@link find}, but emits the index of the |
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* found value, not the value itself.</span> |
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* |
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* <img src="./img/findIndex.png" width="100%"> |
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* |
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* `findIndex` searches for the first item in the source Observable that matches |
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* the specified condition embodied by the `predicate`, and returns the |
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* (zero-based) index of the first occurrence in the source. Unlike |
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* {@link first}, the `predicate` is required in `findIndex`, and does not emit |
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* an error if a valid value is not found. |
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* |
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* @example <caption>Emit the index of 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.findIndex(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 find} |
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* @see {@link first} |
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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} An Observable of the index of the first item that |
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* matches the condition. |
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* @method find |
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* @owner Observable |
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*/ |
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function findIndex(predicate, thisArg) { |
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return function (source) { return source.lift(new find_1.FindValueOperator(predicate, source, true, thisArg)); }; |
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} |
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exports.findIndex = findIndex; |
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//# sourceMappingURL=findIndex.js.map
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