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author | Alex Early <alexander.early@gmail.com> | 2017-04-06 22:46:22 -0700 |
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committer | GitHub <noreply@github.com> | 2017-04-06 22:46:22 -0700 |
commit | 7aa90f39cf8ed4e92a9c939f0521ce1482312c67 (patch) | |
tree | f4084b132306af7702050ebbeaadc0fff47b2b90 | |
parent | b3679d50bee2a98c7b399ed7cbb6cc0081c578e5 (diff) | |
parent | 465cfe8c919d949e12a1c3215d9eb616cdccc910 (diff) | |
download | async-7aa90f39cf8ed4e92a9c939f0521ce1482312c67.tar.gz |
Merge pull request #1365 from alFReD-NSH/try
Add async.tryEach
-rw-r--r-- | lib/index.js | 3 | ||||
-rw-r--r-- | lib/tryEach.js | 58 | ||||
-rw-r--r-- | mocha_test/tryEach.js | 86 |
3 files changed, 147 insertions, 0 deletions
diff --git a/lib/index.js b/lib/index.js index f1e8e98..0e2e457 100644 --- a/lib/index.js +++ b/lib/index.js @@ -134,6 +134,7 @@ import times from './times'; import timesLimit from './timesLimit'; import timesSeries from './timesSeries'; import transform from './transform'; +import tryEach from './tryEach'; import unmemoize from './unmemoize'; import until from './until'; import waterfall from './waterfall'; @@ -211,6 +212,7 @@ export default { timesLimit: timesLimit, timesSeries: timesSeries, transform: transform, + tryEach: tryEach, unmemoize: unmemoize, until: until, waterfall: waterfall, @@ -306,6 +308,7 @@ export { timesLimit as timesLimit, timesSeries as timesSeries, transform as transform, + tryEach as tryEach, unmemoize as unmemoize, until as until, waterfall as waterfall, diff --git a/lib/tryEach.js b/lib/tryEach.js new file mode 100644 index 0000000..d87245f --- /dev/null +++ b/lib/tryEach.js @@ -0,0 +1,58 @@ +import noop from 'lodash/noop'; +import eachSeries from './eachSeries'; +import rest from './internal/rest'; + +/** + * 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.try([ + * 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. + * }); + * + */ +export default function tryEach(tasks, callback) { + var error = null; + var result; + callback = callback || noop; + eachSeries(tasks, function(task, callback) { + task(rest(function (err, args) { + if (args.length <= 1) { + args = args[0]; + } + error = err; + result = args; + callback(!err); + })); + }, function () { + callback(error, result); + }); +} diff --git a/mocha_test/tryEach.js b/mocha_test/tryEach.js new file mode 100644 index 0000000..5e997a6 --- /dev/null +++ b/mocha_test/tryEach.js @@ -0,0 +1,86 @@ +var async = require('../lib'); +var expect = require('chai').expect; +var assert = require('assert'); + +describe('try', function () { + it('no callback', function () { + async.tryEach([]); + }); + it('empty', function (done) { + async.tryEach([], function (err, results) { + expect(err).to.equal(null); + expect(results).to.eql(undefined); + done(); + }); + }); + it('one task, multiple results', function (done) { + var RESULTS = ['something', 'something2']; + async.tryEach([ + function (callback) { + callback(null, RESULTS[0], RESULTS[1]); + } + ], function (err, results) { + expect(err).to.equal(null); + expect(results).to.eql(RESULTS); + done(); + }); + }); + it('one task', function (done) { + var RESULT = 'something'; + async.tryEach([ + function (callback) { + callback(null, RESULT); + } + ], function (err, results) { + expect(err).to.equal(null); + expect(results).to.eql(RESULT); + done(); + }); + }); + it('two tasks, one failing', function (done) { + var RESULT = 'something'; + async.tryEach([ + function (callback) { + callback(new Error('Failure'), {}); + }, + function (callback) { + callback(null, RESULT); + } + ], function (err, results) { + expect(err).to.equal(null); + expect(results).to.eql(RESULT); + done(); + }); + }); + it('two tasks, both failing', function (done) { + var ERROR_RESULT = new Error('Failure2'); + async.tryEach([ + function (callback) { + callback(new Error('Should not stop here')); + }, + function (callback) { + callback(ERROR_RESULT); + } + ], function (err, results) { + expect(err).to.equal(ERROR_RESULT); + expect(results).to.eql(undefined); + done(); + }); + }); + it('two tasks, non failing', function (done) { + var RESULT = 'something'; + async.tryEach([ + function (callback) { + callback(null, RESULT); + }, + function () { + assert.fail('Should not been called'); + }, + ], function (err, results) { + expect(err).to.equal(null); + expect(results).to.eql(RESULT); + done(); + }); + }); +}); + |