| import { Observable } from '../Observable'; |
| import { SchedulerLike } from '../types'; |
| /** |
| * Creates an Observable that emits no items to the Observer and immediately |
| * emits an error notification. |
| * |
| * <span class="informal">Just emits 'error', and nothing else. |
| * </span> |
| * |
| *  |
| * |
| * This static operator is useful for creating a simple Observable that only |
| * emits the error notification. It can be used for composing with other |
| * Observables, such as in a {@link mergeMap}. |
| * |
| * ## Examples |
| * ### Emit the number 7, then emit an error |
| * ```ts |
| * import { throwError, concat, of } from 'rxjs'; |
| * |
| * const result = concat(of(7), throwError(new Error('oops!'))); |
| * result.subscribe(x => console.log(x), e => console.error(e)); |
| * |
| * // Logs: |
| * // 7 |
| * // Error: oops! |
| * ``` |
| * |
| * --- |
| * |
| * ### Map and flatten numbers to the sequence 'a', 'b', 'c', but throw an error for 2 |
| * ```ts |
| * import { throwError, interval, of } from 'rxjs'; |
| * import { mergeMap } from 'rxjs/operators'; |
| * |
| * interval(1000).pipe( |
| * mergeMap(x => x === 2 |
| * ? throwError('Twos are bad') |
| * : of('a', 'b', 'c') |
| * ), |
| * ).subscribe(x => console.log(x), e => console.error(e)); |
| * |
| * // Logs: |
| * // a |
| * // b |
| * // c |
| * // a |
| * // b |
| * // c |
| * // Twos are bad |
| * ``` |
| * |
| * @see {@link Observable} |
| * @see {@link empty} |
| * @see {@link never} |
| * @see {@link of} |
| * |
| * @param {any} error The particular Error to pass to the error notification. |
| * @param {SchedulerLike} [scheduler] A {@link SchedulerLike} to use for scheduling |
| * the emission of the error notification. |
| * @return {Observable} An error Observable: emits only the error notification |
| * using the given error argument. |
| * @static true |
| * @name throwError |
| * @owner Observable |
| */ |
| export declare function throwError(error: any, scheduler?: SchedulerLike): Observable<never>; |