v3.0.1

Bug fixes

• Fixed a regression where arrays passed to queue and cargo would be completely flattened. (#1645)
• Clarified Async's browser support (#1643)

v3.0.0

The async/await release!

There are a lot of new features and subtle breaking changes in this major version, but the biggest feature is that most Async methods return a Promise if you omit the callback, meaning you can await them from within an async function.

const results = await async.mapLimit(urls, 5, async url => {
    const resp = await fetch(url)
    return resp.body
})

Breaking Changes

• Most Async methods return a Promise when the final callback is omitted, making them await-able! (#1572)
• We are now making heavy use of ES2015 features, this means we have dropped out-of-the-box support for Node 4 and earlier, and many old versions of browsers. (#1541, #1553)
• In queue, priorityQueue, cargo and cargoQueue, the "event"-style methods, like q.drain and q.saturated are now methods that register a callback, rather than properties you assign a callback to. They are now of the form q.drain(callback). If you do not pass a callback a Promise will be returned for the next occurrence of the event, making them await-able, e.g. await q.drain(). (#1586, #1641)
• Calling callback(false) will cancel an async method, preventing further iteration and callback calls. This is useful for preventing memory leaks when you break out of an async flow by calling an outer callback. (#1064, #1542)
• during and doDuring have been removed, and instead whilst, doWhilst, until and doUntil now have asynchronous test functions. (#850, #1557)
• limits of less than 1 now cause an error to be thrown in queues and collection methods. (#1249, #1552)
• memoize no longer memoizes errors (#1465, #1466)
• applyEach/applyEachSeries have a simpler interface, to make them more easily type-able. It always returns a function that takes in a single callback argument. If that callback is omitted, a promise is returned, making it awaitable. (#1228, #1640)

New Features

• Async generators are now supported in all the Collection methods. (#1560)
• Added cargoQueue, a queue with both concurrency and payload size parameters. (#1567)
• Queue objects returned from queue now have a Symbol.iterator method, meaning they can be iterated over to inspect the current list of items in the queue. (#1459, #1556)
• A ESM-flavored async.mjs is included in the async package. This is described in the package.json "module" field, meaning it should be automatically used by Webpack and other compatible bundlers.

Bug fixes

• Better handle arbitrary error objects in asyncify (#1568, #1569)

Other

• Removed Lodash as a dependency (#1283, #1528)
• Miscellaneous docs fixes (#1393, #1501, #1540, #1543, #1558, #1563, #1564, #1579, #1581)
• Miscellaneous test fixes (#1538)

v2.6.1

• Updated lodash to prevent npm audit warnings. (#1532, #1533)
• Made async-es more optimized for webpack users (#1517)
• Fixed a stack overflow with large collections and a synchronous iterator (#1514)
• Various small fixes/chores (#1505, #1511, #1527, #1530)

v2.6.0

• Added missing aliases for many methods. Previously, you could not (e.g.) require('async/find') or use async.anyLimit. (#1483)
• Improved queue performance. (#1448, #1454)
• Add missing sourcemap (#1452, #1453)
• Various doc updates (#1448, #1471, #1483)

v2.5.0

• Added concatLimit, the Limit equivalent of concat (#1426, #1430)
• concat improvements: it now preserves order, handles falsy values and the iteratee callback takes a variable number of arguments (#1437, #1436)
• Fixed an issue in queue where there was a size discrepancy between workersList().length and running() (#1428, #1429)
• Various doc fixes (#1422, #1424)

v2.4.1

• Fixed a bug preventing functions wrapped with timeout() from being re-used. (#1418, #1419)

v2.4.0

• Added tryEach, for running async functions in parallel, where you only expect one to succeed. (#1365, #687)
• Improved performance, most notably in parallel and waterfall (#1395)
• Added queue.remove(), for removing items in a queue (#1397, #1391)
• Fixed using eval, preventing Async from running in pages with Content Security Policy (#1404, #1403)
• Fixed errors thrown in an asyncifyed function's callback being caught by the underlying Promise (#1408)
• Fixed timing of queue.empty() (#1367)
• Various doc fixes (#1314, #1394, #1412)

v2.3.0

• Added support for ES2017 async functions. Wherever you can pass a Node-style/CPS function that uses a callback, you can also pass an async function. Previously, you had to wrap async functions with asyncify. The caveat is that it will only work if async functions are supported natively in your environment, transpiled implementations can't be detected. (#1386, #1390)
• Small doc fix (#1392)