source: imaps-frontend/node_modules/p-locate/index.js

'use strict';
const pLimit = require('p-limit');

class EndError extends Error {
        constructor(value) {
                super();
                this.value = value;
        }
}

// The input can also be a promise, so we await it
const testElement = async (element, tester) => tester(await element);

// The input can also be a promise, so we `Promise.all()` them both
const finder = async element => {
        const values = await Promise.all(element);
        if (values[1] === true) {
                throw new EndError(values[0]);
        }

        return false;
};

const pLocate = async (iterable, tester, options) => {
        options = {
                concurrency: Infinity,
                preserveOrder: true,
                ...options
        };

        const limit = pLimit(options.concurrency);

        // Start all the promises concurrently with optional limit
        const items = [...iterable].map(element => [element, limit(testElement, element, tester)]);

        // Check the promises either serially or concurrently
        const checkLimit = pLimit(options.preserveOrder ? 1 : Infinity);

        try {
                await Promise.all(items.map(element => checkLimit(finder, element)));
        } catch (error) {
                if (error instanceof EndError) {
                        return error.value;
                }

                throw error;
        }
};

module.exports = pLocate;