wed
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Wed is a schema-aware editor for XML documents.
34 lines (31 loc) • 1.71 kB
JavaScript
define(function(require,exports,module){
import { EmptyError } from '../util/EmptyError';
import { filter } from './filter';
import { takeLast } from './takeLast';
import { throwIfEmpty } from './throwIfEmpty';
import { defaultIfEmpty } from './defaultIfEmpty';
import { identity } from '../util/identity';
/**
* Returns an Observable that emits only the last item emitted by the source Observable.
* It optionally takes a predicate function as a parameter, in which case, rather than emitting
* the last item from the source Observable, the resulting Observable will emit the last item
* from the source Observable that satisfies the predicate.
*
* <img src="./img/last.png" width="100%">
*
* @throws {EmptyError} Delivers an EmptyError to the Observer's `error`
* callback if the Observable completes before any `next` notification was sent.
* @param {function} [predicate] - The condition any source emitted item has to satisfy.
* @param {any} [defaultValue] - An optional default value to provide if last
* predicate isn't met or no values were emitted.
* @return {Observable} An Observable that emits only the last item satisfying the given condition
* from the source, or an NoSuchElementException if no such items are emitted.
* @throws - Throws if no items that match the predicate are emitted by the source Observable.
*/
export function last(predicate, defaultValue) {
const hasDefaultValue = arguments.length >= 2;
return (source) => source.pipe(predicate ? filter((v, i) => predicate(v, i, source)) : identity, takeLast(1), hasDefaultValue ? defaultIfEmpty(defaultValue) : throwIfEmpty(() => new EmptyError()));
}
//# sourceMappingURL=last.js.map
return module.exports;
});