JAVASCRIPT   8

tryEach.js

Guest on 21st May 2021 06:50:45 AM

  1. 'use strict';
  2.  
  3. Object.defineProperty(exports, "__esModule", {
  4.     value: true
  5. });
  6. exports.default = tryEach;
  7.  
  8. var _noop = require('lodash/noop');
  9.  
  10. var _noop2 = _interopRequireDefault(_noop);
  11.  
  12. var _eachSeries = require('./eachSeries');
  13.  
  14. var _eachSeries2 = _interopRequireDefault(_eachSeries);
  15.  
  16. var _wrapAsync = require('./internal/wrapAsync');
  17.  
  18. var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
  19.  
  20. var _slice = require('./internal/slice');
  21.  
  22. var _slice2 = _interopRequireDefault(_slice);
  23.  
  24. function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
  25.  
  26. /**
  27.  * It runs each task in series but stops whenever any of the functions were
  28.  * successful. If one of the tasks were successful, the `callback` will be
  29.  * passed the result of the successful task. If all tasks fail, the callback
  30.  * will be passed the error and result (if any) of the final attempt.
  31.  *
  32.  * @name tryEach
  33.  * @static
  34.  * @memberOf module:ControlFlow
  35.  * @method
  36.  * @category Control Flow
  37.  * @param {Array|Iterable|Object} tasks - A collection containing functions to
  38.  * run, each function is passed a `callback(err, result)` it must call on
  39.  * completion with an error `err` (which can be `null`) and an optional `result`
  40.  * value.
  41.  * @param {Function} [callback] - An optional callback which is called when one
  42.  * of the tasks has succeeded, or all have failed. It receives the `err` and
  43.  * `result` arguments of the last attempt at completing the `task`. Invoked with
  44.  * (err, results).
  45.  * @example
  46.  * async.tryEach([
  47.  *     function getDataFromFirstWebsite(callback) {
  48.  *         // Try getting the data from the first website
  49.  *         callback(err, data);
  50.  *     },
  51.  *     function getDataFromSecondWebsite(callback) {
  52.  *         // First website failed,
  53.  *         // Try getting the data from the backup website
  54.  *         callback(err, data);
  55.  *     }
  56.  * ],
  57.  * // optional callback
  58.  * function(err, results) {
  59.  *     Now do something with the data.
  60.  * });
  61.  *
  62.  */
  63. function tryEach(tasks, callback) {
  64.     var error = null;
  65.     var result;
  66.     callback = callback || _noop2.default;
  67.     (0, _eachSeries2.default)(tasks, function (task, callback) {
  68.         (0, _wrapAsync2.default)(task)(function (err, res /*, ...args*/) {
  69.             if (arguments.length > 2) {
  70.                 result = (0, _slice2.default)(arguments, 1);
  71.             } else {
  72.                 result = res;
  73.             }
  74.             error = err;
  75.             callback(!err);
  76.         });
  77.     }, function () {
  78.         callback(error, result);
  79.     });
  80. }
  81. module.exports = exports['default'];

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