@reactivex/ix-esnext-esm/asynciterable/zip.js

The Interactive Extensions for JavaScript

import { AsyncIterableX } from './asynciterablex';
import { identityAsync } from '../util/identity';
import { returnAsyncIterator } from '../util/returniterator';
export class ZipAsyncIterable extends AsyncIterableX {
    constructor(sources, fn) {
        super();
        this._sources = sources;
        this._fn = fn;
    }
    // eslint-disable-next-line consistent-return
    async *[Symbol.asyncIterator]() {
        const fn = this._fn;
        const sourcesLength = this._sources.length;
        const its = this._sources.map(x => x[Symbol.asyncIterator]());
        while (sourcesLength > 0) {
            const values = new Array(sourcesLength);
            for (let i = -1; ++i < sourcesLength;) {
                const result = await its[i].next();
                if (result.done) {
                    await Promise.all(its.map(returnAsyncIterator));
                    return undefined;
                }
                values[i] = result.value;
            }
            yield await fn(values);
        }
    }
}
export function zip(...sources) {
    let fn = (sources.shift() || identityAsync);
    if (fn && typeof fn !== 'function') {
        sources.unshift(fn);
        fn = identityAsync;
    }
    return new ZipAsyncIterable(sources, fn);
}

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