Implements Zones for JavaScript https://github.com/angular/zone.js

trevorade and mhevery Fix ZoneAwarePromise.all to resolve at the correct time (#1150 )

For ZoneAwarePromise.all, as [implemented](https://github.com/angular/zone.js/blob/7201d44451f6c67eac2b86eca3cbfafde14035d6/lib/common/promise.ts), the `count` variable serves three purposes:

1.  Count the number of values passed-in
2.  Specify the index of a resolved value in `resolvedValues`
3.  Track when all the promises have been resolved.

In the event that `value.then` is immediately called, `count` will be decremented at the incorrect time resulting in a potentially negative value or reaching 0 when not all values have actually been resolved. 

The fix is to be more meticulous about using the correct indices at the correct time and to not overload the count and number of resolved promises.  This updated version is more explicit about the purpose of the `unresolvedCount` and `valueIndex` variables.  `unresolvedCount` needs to start at 2 to prevent `resolve` from being called too soon in the event that `value.then` calls the callback immediately. The scoping of the index for use in `resolvedValues` is made constant to guarantee the correct index is used.

This buggy behavior specifically manifested as an issue in the Monaco editor but most likely occurs elsewhere as well in cases where promises may immediately call into `.then`.

Related issue:
Microsoft/monaco-editor#790 (comment)

Latest commit 9ed5712

Oct 26, 2018

README.md

Zone.js

Implements Zones for JavaScript, inspired by Dart.

If you're using zone.js via unpkg (i.e. using https://unpkg.com/zone.js) and you're using any of the following libraries, make sure you import them first

'newrelic' as it patches global.Promise before zone.js does

'async-listener' as it patches global.setTimeout, global.setInterval before zone.js does

'continuation-local-storage' as it uses async-listener

NEW Zone.js POST-v0.6.0

See the new API here.

Read up on Zone Primer.

What's a Zone?

A Zone is an execution context that persists across async tasks. You can think of it as thread-local storage for JavaScript VMs.

See this video from ng-conf 2014 for a detailed explanation:

See also

async-listener - a similar library for node
Async stack traces in Chrome
strongloop/zone (Deprecated)
vizone - control flow visualizer that uses zone.js

Standard API support

zone.js patched most standard web APIs (such as DOM events, XMLHttpRequest, ...) and nodejs APIs (EventEmitter, fs, ...), for more details, please see STANDARD-APIS.md.

Nonstandard API support

We are adding support to some nonstandard APIs, such as MediaQuery and Notification. Please see NON-STANDARD-APIS.md for more details.

Examples

You can find some samples to describe how to use zone.js in SAMPLE.md.

Modules

zone.js patches the async APIs described above, but those patches will have some overhead. Starting from zone.js v0.8.9, you can choose which web API module you want to patch. For more details, please see MODULE.md.

Promise A+ test passed

License

MIT

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