ix/asynciterable/max.mjs

The Interactive Extensions for JavaScript

import { __awaiter } from "tslib";
import { equalityComparerAsync } from '../util/comparer.mjs';
import { identityAsync } from '../util/identity.mjs';
import { wrapWithAbort } from './operators/withabort.mjs';
import { throwIfAborted } from '../aborterror.mjs';
/**
 * Returns the maximum element with the optional selector.
 *
 * @template TSource The type of the elements in the source sequence.
 * @param {AsyncIterable<TSource>} source An async-iterable sequence to determine the maximum element of.
 * @param {ExtremaByOptions<TKey>} [options] The options which include an optional comparer and abort signal.
 * @returns {Promise<TResult>} The maximum element.
 */
export function max(source, options) {
    return __awaiter(this, void 0, void 0, function* () {
        const { ['comparer']: comparer = equalityComparerAsync, ['signal']: signal, ['selector']: selector = identityAsync, } = options || {};
        throwIfAborted(signal);
        const it = wrapWithAbort(source, signal)[Symbol.asyncIterator]();
        let next = yield it.next();
        if (next.done) {
            throw new Error('Sequence contains no elements');
        }
        let maxValue = yield selector(next.value);
        while (!(next = yield it.next()).done) {
            const current = yield selector(next.value);
            if ((yield comparer(current, maxValue)) > 0) {
                maxValue = current;
            }
        }
        return maxValue;
    });
}

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