async/tryEach.js

'use strict';

Object.defineProperty(exports, "__esModule", {
    value: true
});

var _eachSeries = require('./eachSeries');

var _eachSeries2 = _interopRequireDefault(_eachSeries);

var _wrapAsync = require('./internal/wrapAsync');

var _wrapAsync2 = _interopRequireDefault(_wrapAsync);

var _awaitify = require('./internal/awaitify');

var _awaitify2 = _interopRequireDefault(_awaitify);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * It runs each task in series but stops whenever any of the functions were
 * successful. If one of the tasks were successful, the `callback` will be
 * passed the result of the successful task. If all tasks fail, the callback
 * will be passed the error and result (if any) of the final attempt.
 *
 * @name tryEach
 * @static
 * @memberOf module:ControlFlow
 * @method
 * @category Control Flow
 * @param {Array|Iterable|AsyncIterable|Object} tasks - A collection containing functions to
 * run, each function is passed a `callback(err, result)` it must call on
 * completion with an error `err` (which can be `null`) and an optional `result`
 * value.
 * @param {Function} [callback] - An optional callback which is called when one
 * of the tasks has succeeded, or all have failed. It receives the `err` and
 * `result` arguments of the last attempt at completing the `task`. Invoked with
 * (err, results).
 * @returns {Promise} a promise, if no callback is passed
 * @example
 * async.tryEach([
 *     function getDataFromFirstWebsite(callback) {
 *         // Try getting the data from the first website
 *         callback(err, data);
 *     },
 *     function getDataFromSecondWebsite(callback) {
 *         // First website failed,
 *         // Try getting the data from the backup website
 *         callback(err, data);
 *     }
 * ],
 * // optional callback
 * function(err, results) {
 *     Now do something with the data.
 * });
 *
 */
function tryEach(tasks, callback) {
    var error = null;
    var result;
    return (0, _eachSeries2.default)(tasks, (task, taskCb) => {
        (0, _wrapAsync2.default)(task)((err, ...args) => {
            if (err === false) return taskCb(err);

            if (args.length < 2) {
                [result] = args;
            } else {
                result = args;
            }
            error = err;
            taskCb(err ? null : {});
        });
    }, () => callback(error, result));
}

exports.default = (0, _awaitify2.default)(tryEach);
module.exports = exports['default'];