added unit testing, and started implementing unit tests...phew

node_modules/async/tryEach.js

@@ -0,0 +1,81 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = tryEach;
+
+var _noop = require('lodash/noop');
+
+var _noop2 = _interopRequireDefault(_noop);
+
+var _eachSeries = require('./eachSeries');
+
+var _eachSeries2 = _interopRequireDefault(_eachSeries);
+
+var _wrapAsync = require('./internal/wrapAsync');
+
+var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
+
+var _slice = require('./internal/slice');
+
+var _slice2 = _interopRequireDefault(_slice);
+
+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|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).
+ * @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;
+    callback = callback || _noop2.default;
+    (0, _eachSeries2.default)(tasks, function (task, callback) {
+        (0, _wrapAsync2.default)(task)(function (err, res /*, ...args*/) {
+            if (arguments.length > 2) {
+                result = (0, _slice2.default)(arguments, 1);
+            } else {
+                result = res;
+            }
+            error = err;
+            callback(!err);
+        });
+    }, function () {
+        callback(error, result);
+    });
+}
+module.exports = exports['default'];