@reactivex/rxjs/dist/es6/operator/defaultIfEmpty.js

Reactive Extensions for modern JavaScript

import { Subscriber } from '../Subscriber';
/**
 * Returns an Observable that emits the elements of the source or a specified default value if empty.
 * @param {any} defaultValue the default value used if source is empty; defaults to null.
 * @return {Observable} an Observable of the items emitted by the where empty values are replaced by the specified default value or null.
 * @method defaultIfEmpty
 * @owner Observable
 */
export function defaultIfEmpty(defaultValue = null) {
    return this.lift(new DefaultIfEmptyOperator(defaultValue));
}
class DefaultIfEmptyOperator {
    constructor(defaultValue) {
        this.defaultValue = defaultValue;
    }
    call(subscriber, source) {
        return source._subscribe(new DefaultIfEmptySubscriber(subscriber, this.defaultValue));
    }
}
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
class DefaultIfEmptySubscriber extends Subscriber {
    constructor(destination, defaultValue) {
        super(destination);
        this.defaultValue = defaultValue;
        this.isEmpty = true;
    }
    _next(value) {
        this.isEmpty = false;
        this.destination.next(value);
    }
    _complete() {
        if (this.isEmpty) {
            this.destination.next(this.defaultValue);
        }
        this.destination.complete();
    }
}
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