es6/observable/ErrorObservable.js

import { Observable } from '../Observable';
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @extends {Ignored}
 * @hide true
 */
export class ErrorObservable extends Observable {
    constructor(error, scheduler) {
        super();
        this.error = error;
        this.scheduler = scheduler;
    }
    /**
     * 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>
     *
     * <img src="./img/throw.png" width="100%">
     *
     * 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}.
     *
     * @example <caption>Emit the number 7, then emit an error.</caption>
     * var result = Rx.Observable.throw(new Error('oops!')).startWith(7);
     * result.subscribe(x => console.log(x), e => console.error(e));
     *
     * @example <caption>Map and flatten numbers to the sequence 'a', 'b', 'c', but throw an error for 13</caption>
     * var interval = Rx.Observable.interval(1000);
     * var result = interval.mergeMap(x =>
     *   x === 13 ?
     *     Rx.Observable.throw('Thirteens are bad') :
     *     Rx.Observable.of('a', 'b', 'c')
     * );
     * result.subscribe(x => console.log(x), e => console.error(e));
     *
     * @see {@link create}
     * @see {@link empty}
     * @see {@link never}
     * @see {@link of}
     *
     * @param {any} error The particular Error to pass to the error notification.
     * @param {Scheduler} [scheduler] A {@link IScheduler} 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 throw
     * @owner Observable
     */
    static create(error, scheduler) {
        return new ErrorObservable(error, scheduler);
    }
    static dispatch(arg) {
        const { error, subscriber } = arg;
        subscriber.error(error);
    }
    _subscribe(subscriber) {
        const error = this.error;
        const scheduler = this.scheduler;
        subscriber.syncErrorThrowable = true;
        if (scheduler) {
            return scheduler.schedule(ErrorObservable.dispatch, 0, {
                error, subscriber
            });
        }
        else {
            subscriber.error(error);
        }
    }
}
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