• Q.any now annotates its error message to clarify that Q.any was involved and includes only the last error emitted. (Ivan Etchart)
  • Avoid domain.dispose during tests in preparation for Node.js 9. (Anna Henningsen)


  • Q.any gives an error message from the last rejected promise
  • Throw if callback supplied to “finally” is invalid (@grahamrhay)
  • Long stack trace improvements, can now construct long stack traces across rethrows.


  • Address an issue that prevented Q from being used as a <script> for Firefox add-ons. Q can now be used in any environment that provides window or self globals, favoring window since add-ons have an an immutable self that is distinct from window.


  • Add noConflict support for use in <script> (@jahnjw).


  • Add tracking for unhandled and handled rejections in Node.js (@benjamingr).


  • Fix Node.js environment detection for modern Browserify (@kahnjw).


  • Added Q.any(promisesArray) method (@vergara). Returns a promise fulfilled with the value of the first resolved promise in promisesArray. If all promises in promisesArray are rejected, it returns a rejected promise.


  • Removed extraneous files from the npm package by using the “files” whitelist in package.json instead of the .npmignore blacklist. (@anton-rudeshko)


  • Fix a pair of regressions in bootstrapping, one which precluded WebWorker support, and another that precluded support in <script> usage outright. #607


  • Adds support for enabling long stack traces in node.js by setting environment variable Q_DEBUG=1.
  • Introduces the tap method to promises, which will see a value pass through without alteration.
  • Use instanceof to recognize own promise instances as opposed to thenables.
  • Construct timeout errors with code === ETIMEDOUT (Kornel Lesiński)
  • More descriminant CommonJS module environment detection.
  • Dropped continuous integration for Node.js 0.6 and 0.8 because of changes to npm that preclude the use of new ^ version predicate operator in any transitive dependency.
  • Users can now override Q.nextTick.


  • Adds support for Q.Promise, which implements common usage of the ES6 Promise constructor and its methods. Promise does not have a valid promise constructor and a proper implementation awaits version 2 of Q.
  • Removes the console stopgap for a promise inspector. This no longer works with any degree of reliability.
  • Fixes support for content security policies that forbid eval. Now using the StopIteration global to distinguish SpiderMonkey generators from ES6 generators, assuming that they will never coexist.


:cake: This is all but a re-release of version 0.9, which has settled into a gentle maintenance mode and rightly deserves an official 1.0. An ambitious 2.0 release is already around the corner, but 0.9/1.0 have been distributed far and wide and demand long term support.

  • Q will now attempt to post a debug message in browsers regardless of whether window.Touch is defined. Chrome at least now has this property regardless of whether touch is supported by the underlying hardware.
  • Remove deprecation warning from promise.valueOf. The function is called by the browser in various ways so there is no way to distinguish usage that should be migrated from usage that cannot be altered.


  • :warning: q.min.js is no longer checked-in. It is however still created by Grunt and NPM.
  • Fixes a bug that inhibited Q.async with implementations of the new ES6 generators.
  • Fixes a bug with nextTick affecting Safari 6.0.5 the first time a page loads when an iframe is involved.
  • Introduces passByCopy, join, and race.
  • Shows stack traces or error messages on the console, instead of Error objects.
  • Elimintates wrapper methods for improved performance.
  • Q.all now propagates progress notifications of the form you might expect of ES6 iterations, {value, index} where the value is the progress notification from the promise at index.


  • Fixes a bug in recognizing the difference between compatible Q promises, and Q promises from before the implementation of “inspect”. The latter are now coerced.
  • Fixes an infinite asynchronous coercion cycle introduced by former solution, in two independently sufficient ways. 1.) All promises returned by makePromise now implement “inspect”, albeit a default that reports that the promise has an “unknown” state. 2.) The implementation of “then/when” is now in “then” instead of “when”, so that the responsibility to “coerce” the given promise rests solely in the “when” method and the “then” method may assume that “this” is a promise of the right type.
  • Refactors nextTick to use an unrolled microtask within Q regardless of how new ticks a requested. #316 @rkatic


  • Introduces inspect for getting the state of a promise as {state: "fulfilled" | "rejected" | "pending", value | reason}.
  • Introduces allSettled which produces an array of promises states for the input promises once they have all “settled”. This is in accordance with a discussion on Promises/A+ that “settled” refers to a promise that is “fulfilled” or “rejected”. “resolved” refers to a deferred promise that has been “resolved” to another promise, “sealing its fate” to the fate of the successor promise.
  • Long stack traces are now off by default. Set Q.longStackSupport to true to enable long stack traces.
  • Long stack traces can now follow the entire asynchronous history of a promise, not just a single jump.
  • Introduces spawn for an immediately invoked asychronous generator. @jlongster
  • Support for experimental synonyms mapply, mcall, nmapply, nmcall for method invocation.


  • isPromise and isPromiseAlike now always returns a boolean (even for falsy values). #284 @lfac-pt
  • Support for ES6 Generators in async #288 @andywingo
  • Clear duplicate promise rejections from dispatch methods #238 @SLaks
  • Unhandled rejection API #296 @domenic stopUnhandledRejectionTracking, getUnhandledReasons, resetUnhandledRejections.


  • Add the ability to give Q.timeout’s errors a custom error message. #270 @jgrenon
  • Fix Q’s call-stack busting behavior in Node.js 0.10, by switching from process.nextTick to setImmediate. #254 #259
  • Fix Q’s behavior when used with the Mocha test runner in the browser, since Mocha introduces a fake process global without a nextTick property. #267
  • Fix some, but not all, cases wherein Q would give false positives in its unhandled rejection detection (#252). A fix for other cases (#238) is hopefully coming soon.
  • Made Q.promise throw early if given a non-function.


  • Pass through progress notifications when using timeout. #229 @omares
  • Pass through progress notifications when using delay.
  • Fix nbind to actually bind the thisArg. #232 @davidpadbury


  • Made the AMD detection compatible with the RequireJS optimizer’s namespace option. #225 @terinjokes
  • Fix side effects from valueOf, and thus from isFulfilled, isRejected, and isPending. #226 @benjamn


This release removes many layers of deprecated methods and brings Q closer to alignment with Mark Miller’s TC39 strawman for concurrency. At the same time, it fixes many bugs and adds a few features around error handling. Finally, it comes with an updated and comprehensive API Reference.

API Cleanup

The following deprecated or undocumented methods have been removed. Their replacements are listed here:

0.8.x method 0.9 replacement
Q.ref Q
call, apply, bind (*) fcall/invoke, fapply/post, fbind
ncall, napply (*) nfcall/ninvoke, nfapply/npost
end done
put set
node nbind
nend nodeify
isResolved isPending
deferred.node deferred.makeNodeResolver
Method, sender dispatcher
send dispatch
view, viewInfo (none)

(*) Use of thisp is discouraged. For calling methods, use post or invoke.

Alignment with the Concurrency Strawman

  • Q now exports a Q(value) function, an alias for resolve. Q.call, Q.apply, and Q.bind were removed to make room for the same methods on the function prototype.
  • invoke has been aliased to send in all its forms.
  • post with no method name acts like fapply.

Error Handling

  • Long stack traces can be turned off by setting Q.stackJumpLimit to zero. In the future, this property will be used to fine tune how many stack jumps are retained in long stack traces; for now, anything nonzero is treated as one (since Q only tracks one stack jump at the moment, see #144). #168
  • In Node.js, if there are unhandled rejections when the process exits, they are output to the console. #115


  • delete and set (née put) no longer have a fulfillment value.
  • Q promises are no longer frozen, which helps with performance.
  • thenReject is now included, as a counterpart to thenResolve.
  • The included browser nextTick shim is now faster. #195 @rkatic.

Bug Fixes

  • Q now works in Internet Explorer 10. #186 @ForbesLindesay
  • fbind no longer hard-binds the returned function’s this to undefined. #202
  • Q.reject no longer leaks memory. #148
  • npost with no arguments now works. #207
  • allResolved now works with non-Q promises (“thenables”). #179
  • keys behavior is now correct even in browsers without native Object.keys. #192 @rkatic
  • isRejected and the exception property now work correctly if the rejection reason is falsy. #198

Internals and Advanced

  • The internal interface for a promise now uses dispatchPromise(resolve, op, operands) instead of sendPromise(op, resolve, ...operands), which reduces the cases where Q needs to do argument slicing.
  • The internal protocol uses different operands. “put” is now “set”. “del” is now “delete”. “view” and “viewInfo” have been removed.
  • Q.fulfill has been added. It is distinct from Q.resolve in that it does not pass promises through, nor coerces promises from other systems. The promise becomes the fulfillment value. This is only recommended for use when trying to fulfill a promise with an object that has a then function that is at the same time not a promise.


  • Treat foreign promises as unresolved in Q.isFulfilled; this lets Q.all work on arrays containing foreign promises. #154
  • Fix minor incompliances with the Promises/A+ spec and test suite. #157 #158


  • Added nfcall, nfapply, and nfbind as thisp-less versions of ncall, napply, and nbind. The latter are now deprecated. #142
  • Long stack traces no longer cause linearly-growing memory usage when chaining promises together. #111
  • Inspecting error.stack in a rejection handler will now give a long stack trace. #103
  • Fixed Q.timeout to clear its timeout handle when the promise is rejected; previously, it kept the event loop alive until the timeout period expired. #145 @dfilatov
  • Added q/queue module, which exports an infinite promise queue constructor.


  • Added done as a replacement for end, taking the usual fulfillment, rejection, and progress handlers. It’s essentially equivalent to then(f, r, p).end().
  • Added Q.onerror, a settable error trap that you can use to get full stack traces for uncaught errors. #94
  • Added thenResolve as a shortcut for returning a constant value once a promise is fulfilled. #108 @ForbesLindesay
  • Various tweaks to progress notification, including propagation and transformation of progress values and only forwarding a single progress object.
  • Renamed nend to nodeify. It no longer returns an always-fulfilled promise when a Node callback is passed.
  • deferred.resolve and deferred.reject no longer (sometimes) return deferred.promise.
  • Fixed stack traces getting mangled if they hit end twice. #116 #121 @ef4
  • Fixed ninvoke and npost to work on promises for objects with Node methods. #134
  • Fixed accidental coercion of objects with nontrivial valueOf methods, like Dates, by the promise’s valueOf method. #135
  • Fixed spread not calling the passed rejection handler if given a rejected promise.


  • Added nend
  • Added preliminary progress notification support, via promise.then(onFulfilled, onRejected, onProgress), promise.progress(onProgress), and deferred.notify(...progressData).
  • Made put and del return the object acted upon for easier chaining. #84
  • Fixed coercion cycles with cooperating promises. #106



  • Fixed npost and ninvoke to pass the correct thisp. #74
  • Fixed various cases involving unorthodox rejection reasons. #73 #90 @ef4
  • Fixed double-resolving of misbehaved custom promises. #75
  • Sped up Q.all for arrays contain already-resolved promises or scalar values. @ForbesLindesay
  • Made stack trace filtering work when concatenating assets. #93 @ef4
  • Added warnings for deprecated methods. @ForbesLindesay
  • Added .npmignore file so that dependent packages get a slimmer node_modules directory.


  • Added preliminary support for long traces (@domenic)
  • Added fapply, fcall, fbind for non-thisp promised function calls.
  • Added return for async generators, where generators are implemented.
  • Rejected promises now have an “exception” property. If an object isRejected(object), then object.valueOf().exception will be the wrapped error.
  • Added Jasmine specifications
  • Support Internet Explorers 7–9 (with multiple bug fixes @domenic)
  • Support Firefox 12
  • Support Safari 5.1.5
  • Support Chrome 18


  • WARNING: promise.timeout is now rejected with an Error object and the message now includes the duration of the timeout in miliseconds. This doesn’t constitute (in my opinion) a backward-incompatibility since it is a change of an undocumented and unspecified public behavior, but if you happened to depend on the exception being a string, you will need to revise your code.
  • Added deferred.makeNodeResolver() to replace the more cryptic deferred.node() method.
  • Added experimental Q.promise(maker(resolve, reject)) to make a promise inside a callback, such that thrown exceptions in the callback are converted and the resolver and rejecter are arguments. This is a shorthand for making a deferred directly and inspired by @gozala’s stream constructor pattern and the Microsoft Windows Metro Promise constructor interface.
  • Added experimental Q.begin() that is intended to kick off chains of .then so that each of these can be reordered without having to edit the new and former first step.


  • Added isFulfilled, isRejected, and isResolved to the promise prototype.
  • Added allResolved for waiting for every promise to either be fulfilled or rejected, without propagating an error. @utvara #53
  • Added Q.bind as a method to transform functions that return and throw into promise-returning functions. See an example. @domenic
  • Renamed node export to nbind, and added napply to complete the set. node remains as deprecated. @domenic #58
  • Renamed Method export to sender. Method remains as deprecated and will be removed in the next major version since I expect it has very little usage.
  • Added browser console message indicating a live list of unhandled errors.
  • Added support for msSetImmediate (IE10) or setImmediate (available via polyfill) as a browser-side nextTick implementation. #44 #50 #59
  • Stopped using the event-queue dependency, which was in place for Narwhal support: now directly using process.nextTick.
  • WARNING: EXPERIMENTAL: added finally alias for fin, catch alias for fail, try alias for call, and delete alias for del. These properties are enquoted in the library for cross-browser compatibility, but may be used as property names in modern engines.


  • Deprecated ref in favor of resolve as recommended by @domenic.
  • Update event-queue dependency.


  • Fixed Opera bug. #35 @cadorn
  • Fixed Q.all([]) #32 @domenic


  • WARNING: enqueue removed. Use nextTick instead. This is more consistent with NodeJS and (subjectively) more explicit and intuitive.
  • WARNING: def removed. Use master instead. The term def was too confusing to new users.
  • WARNING: spy removed in favor of fin.
  • WARNING: wait removed. Do all(args).get(0) instead.
  • WARNING: join removed. Do all(args).spread(callback) instead.
  • WARNING: Removed the Q function module.exports alias for Q.ref. It conflicts with Q.apply in weird ways, making it uncallable.
  • Revised delay so that it accepts both (value, timeout) and (timeout) variations based on arguments length.
  • Added ref().spread(cb(...args)), a variant of then that spreads an array across multiple arguments. Useful with all().
  • Added defer().node() Node callback generator. The callback accepts (error, value) or (error, ...values). For multiple value arguments, the fulfillment value is an array, useful in conjunction with spread.
  • Added node and ncall, both with the signature (fun, thisp_opt, ...args). The former is a decorator and the latter calls immediately. node optional binds and partially applies. ncall can bind and pass arguments.


  • Fixed thenable promise assimilation.


  • Stopped shimming Array.prototype.reduce. The enumerable property has bad side-effects. Libraries that depend on this (for example, QQ) will need to be revised.


  • WARNING: Removed report and asap
  • WARNING: The callback argument of the fin function no longer receives any arguments. Thus, it can be used to call functions that should not receive arguments on resolution. Use when, then, or fail if you need a value.
  • IMPORTANT: Fixed a bug in the use of MessageChannel for nextTick.
  • Renamed enqueue to nextTick.
  • Added experimental view and viewInfo for creating views of promises either when or before they’re fulfilled.
  • Shims are now externally applied so subsequent scripts or dependees can use them.
  • Improved minification results.
  • Improved readability.


  • WARNING: In practice, the implementation of spy and the name fin were useful. I’ve removed the old fin implementation and renamed/aliased spy.
  • The “q” module now exports its ref function as a “Q” constructor, with module systems that support exports assignment including NodeJS, RequireJS, and when used as a <script> tag. Notably, strictly compliant CommonJS does not support this, but UncommonJS does.
  • Added async decorator for generators that use yield to “trampoline” promises. In engines that support generators (SpiderMonkey), this will greatly reduce the need for nested callbacks.
  • Made when chainable.
  • Made all chainable.


  • Added all and refactored join and wait to use it. All of these will now reject at the earliest rejection.


  • Minor improvement to spy; now waits for resolution of callback promise.


  • Made most Q API methods chainable on promise objects, and turned the previous promise-methods of join, wait, and report into Q API methods.
  • Added apply and call to the Q API, and apply as a promise handler.
  • Added fail, fin, and spy to Q and the promise prototype for convenience when observing rejection, fulfillment and rejection, or just observing without affecting the resolution.
  • Renamed def (although def remains shimmed until the next major release) to master.
  • Switched to using MessageChannel for next tick task enqueue in browsers that support it.


  • Exceptions are no longer reported when consumed.
  • Removed error from the API. Since exceptions are getting consumed, throwing them in an errback causes the exception to silently disappear. Use end.
  • Added end as both an API method and a promise-chain ending method. It causes propagated rejections to be thrown, which allows Node to write stack traces and emit uncaughtException events, and browsers to likewise emit onerror and log to the console.
  • Added join and wait as promise chain functions, so you can wait for variadic promises, returning your own promise back, or join variadic promises, resolving with a callback that receives variadic fulfillment values.


  • end no longer returns a promise. It is the end of the promise chain.
  • Stopped reporting thrown exceptions in when callbacks and errbacks. These must be explicitly reported through .end(), .then(null, Q.error), or some other mechanism.
  • Added report as an API method, which can be used as an errback to report and propagate an error.
  • Added report as a promise-chain method, so an error can be reported if it passes such a gate.


  • Fixed <script> support that regressed with 0.4.2 because of “use strict” in the module system multi-plexer.


  • Added support for RequireJS (jburke)


  • Added an “end” method to the promise prototype, as a shorthand for waiting for the promise to be resolved gracefully, and failing to do so, to dump an error message.


  • *Removed the utility modules. NPM and Node no longer expose any module except the main module. These have been moved and merged into the “qq” package.
  • *In a non-CommonJS browser, q.js can be used as a script. It now creates a Q global variable.
  • Fixed thenable assimilation.
  • Fixed some issues with asap, when it resolves to undefined, or throws an exception.


  • The post method has been reverted to its original signature, as provided in Tyler Close’s ref_send API. That is, post accepts two arguments, the second of which is an arbitrary object, but usually invocation arguments as an Array. To provide variadic arguments to post, there is a new invoke function that posts the variadic arguments to the value given in the first argument.
  • The defined method has been moved from q to q/util since it gets no use in practice but is still theoretically useful.
  • The Promise constructor has been renamed to makePromise to be consistent with the convention that functions that do not require the new keyword to be used as constructors have camelCase names.
  • The isResolved function has been renamed to isFulfilled. There is a new isResolved function that indicates whether a value is not a promise or, if it is a promise, whether it has been either fulfilled or rejected. The code has been revised to reflect this nuance in terminology.


  • Added join to "q/util" for variadically joining multiple promises.


  • The future-compatible invoke method has been added, to replace post, since post will become backward- incompatible in the next major release.
  • Exceptions thrown in the callbacks of a when call are now emitted to Node’s "uncaughtException" process event in addition to being returned as a rejection reason.


  • Exceptions thrown in the callbacks of a when call are now consumed, warned, and transformed into rejections of the promise returned by when.


  • Fixed a minor bug in thenable assimilation, regressed because of the change in the forwarding protocol.
  • Fixed behavior of “q/util” deep method on dates and other primitives. Github issue #11.


  • Thenables (objects with a “then” method) are accepted and provided, bringing this implementation of Q into conformance with Promises/A, B, and D.
  • Added makePromise, to replace the Promise function eventually.
  • Rejections are now also duck-typed. A rejection is a promise with a valueOf method that returns a rejection descriptor. A rejection descriptor has a “promiseRejected” property equal to “true” and a “reason” property corresponding to the rejection reason.
  • Altered the makePromise API such that the fallback method no longer receives a superfluous resolved method after the operator. The fallback method is responsible only for returning a resolution. This breaks an undocumented API, so third-party API’s depending on the previous undocumented behavior may break.


  • Changed promises into a duck-type such that multiple instances of the Q module can exchange promise objects. A promise is now defined as “an object that implements the promiseSend(op, resolved, ...) method and valueOf”.
  • Exceptions in promises are now captured and returned as rejections.


  • Fixed bug in ref that prevented del messages from being received (gozala)
  • Fixed a conflict with FireFox 4; constructor property is now read-only.


  • Added keys message to promises and to the promise API.


  • Added boilerplate to q/queue and q/util.
  • Fixed missing dependency to q/queue.


  • The resolve and reject methods of defer objects now return the resolution promise for convenience.
  • Added q/util, which provides step, delay, shallow, deep, and three reduction orders.
  • Added q/queue module for a promise Queue.
  • Added q-comm to the list of compatible libraries.
  • Deprecated defined from q, with intent to move it to q/util.


  • Changed post(ref, name, args) to variadic post(ref, name, …args). BACKWARD INCOMPATIBLE
  • Added a def(value) method to annotate an object as being necessarily a local value that cannot be serialized, such that inter-process/worker/vat promise communication libraries will send messages to it, but never send it back.
  • Added a send(value, op, …args) method to the public API, for forwarding messages to a value or promise in a future turn.


  • Added isRejected() for testing whether a value is a rejected promise. isResolved() retains the behavior of stating that rejected promises are not resolved.


  • Fixed isResolved(null) and isResolved(undefined) [issue #9]
  • Fixed a problem with the Object.create shim


  • shimmed ES5 Object.create in addition to Object.freeze for compatibility on non-ES5 engines (gozala)


  • Q.isResolved added
  • promise.valueOf() now returns the value of resolved and near values
  • asap retried
  • promises are frozen when possible


  • fixed dependency list for Teleport (gozala)
  • all unit tests now pass (gozala)


  • added support for Teleport as an engine (gozala)
  • simplified and updated methods for getting internal print and enqueue functions universally (gozala)


  • fixed erroneous link to the q module in package.json


  • restructured for overlay style package compatibility


  • removed asap because it was broken, probably down to the philosophy.


  • removed q-util
  • fixed asap so it returns a value if completed


  • added q-util


  • initial version