Intent to replace Promise.jsm and promise.js with DOM Promises

David Rajchenbach-Teller dteller at
Tue Nov 19 17:05:49 UTC 2013

Generally, I believe that it's a good idea, if DOM Promises have the
equivalent of:

Is this the case already?


On 11/19/13 1:38 AM, Nikhil Marathe wrote:
> (Cross posted to firefox-dev, please reply on dev.platform)
> DOM Promise has been in the tree for a while, and is enabled for
> ChromeWorkers and certified apps. With a couple of patches, it will achieve
> conformance with the AP2 spec [1], which is what TC39 has accepted as the
> bare minimum for Promises in ECMA6. It will also be available on Workers as
> long as the pref is enabled. We currently have two JS promise
> implementations in our codebase:
> toolkit/modules/Promise.jsm
> addon-sdk <>/source<>
> /lib <>/
> sdk<>
> /core<>
> /promise.js<>
> which offer a different API and reimplement some code, one for chrome, one
> for content.
> My intention is:
> 1) Enable Promises for all chrome code.
> 2) Set dom.promise.enabled to true for tests
> 3) Migrate all users of the two promise implementations to the new style
> (including tests).
> 4) Get rid of these two JS implementations.
> The work is being tracked in Bug 939636 [2].
> It would be a great help if developers who work on code using Promises
> could download the patch that enables Promises in chrome and submit patches
> to that bug updating code/tests.
> The new spec has a different style of creating promises, which may not
> interface well with callback oriented code. Feel free to ping me (nsm on
> IRC) if you need help.
> If there is a reason this shouldn't be done, please let me know.
> At some point in the future Spidermonkey will implement Promises natively,
> at which point (theoretically) all the code can simply transition to that
> with no changes.
> Nikhil
> [1]
> [2]
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David Rajchenbach-Teller, PhD
 Performance Team, Mozilla

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