| import { Observable } from '../Observable'; |
| import { OperatorFunction } from '../types'; |
| /** |
| * Emits only the index of the first value emitted by the source Observable that |
| * meets some condition. |
| * |
| * <span class="informal">It's like {@link find}, but emits the index of the |
| * found value, not the value itself.</span> |
| * |
| *  |
| * |
| * `findIndex` searches for the first item in the source Observable that matches |
| * the specified condition embodied by the `predicate`, and returns the |
| * (zero-based) index of the first occurrence in the source. Unlike |
| * {@link first}, the `predicate` is required in `findIndex`, and does not emit |
| * an error if a valid value is not found. |
| * |
| * ## Example |
| * Emit the index of first click that happens on a DIV element |
| * ```ts |
| * import { fromEvent } from 'rxjs'; |
| * import { findIndex } from 'rxjs/operators'; |
| * |
| * const clicks = fromEvent(document, 'click'); |
| * const result = clicks.pipe(findIndex(ev => ev.target.tagName === 'DIV')); |
| * result.subscribe(x => console.log(x)); |
| * ``` |
| * |
| * @see {@link filter} |
| * @see {@link find} |
| * @see {@link first} |
| * @see {@link take} |
| * |
| * @param {function(value: T, index: number, source: Observable<T>): boolean} predicate |
| * A function called with each item to test for condition matching. |
| * @param {any} [thisArg] An optional argument to determine the value of `this` |
| * in the `predicate` function. |
| * @return {Observable} An Observable of the index of the first item that |
| * matches the condition. |
| * @method find |
| * @owner Observable |
| */ |
| export declare function findIndex<T>(predicate: (value: T, index: number, source: Observable<T>) => boolean, thisArg?: any): OperatorFunction<T, number>; |
