ix/asynciterable/average.mjs

The Interactive Extensions for JavaScript

import { __asyncValues, __awaiter } from "tslib";
import { identityAsync } from '../util/identity.mjs';
import { wrapWithAbort } from './operators/withabort.mjs';
import { throwIfAborted } from '../aborterror.mjs';
/**
 * Computes the average of the async-iterable sequence.
 *
 * @param {AsyncIterable<any>} source source async-iterable sequence to compute the average.
 * @param {AverageOptions<any>} [options] The options for calculating the average.
 * @returns {Promise<number>} A Promise which returns the computed average for the async-iterable sequence.
 */
export function average(source, options) {
    var _a, e_1, _b, _c;
    return __awaiter(this, void 0, void 0, function* () {
        const { ['selector']: selector = identityAsync, ['signal']: signal, ['thisArg']: thisArg, } = options || {};
        throwIfAborted(signal);
        let sum = 0;
        let count = 0;
        try {
            for (var _d = true, _e = __asyncValues(wrapWithAbort(source, signal)), _f; _f = yield _e.next(), _a = _f.done, !_a; _d = true) {
                _c = _f.value;
                _d = false;
                const item = _c;
                sum += yield selector.call(thisArg, item, signal);
                count++;
            }
        }
        catch (e_1_1) { e_1 = { error: e_1_1 }; }
        finally {
            try {
                if (!_d && !_a && (_b = _e.return)) yield _b.call(_e);
            }
            finally { if (e_1) throw e_1.error; }
        }
        if (count === 0) {
            throw new Error('Empty collection');
        }
        return sum / count;
    });
}

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