Intent to Ship: Expose ReadableStreamDefaultController interface
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Nidhi Jaju
Dec 8, 2020, 4:10:59 AM12/8/20
to blink-dev, Adam Rice
Contact emails
nidh...@google.com, ri...@chromium.orgExplainer
https://github.com/whatwg/streams/issues/963https://github.com/whatwg/streams/pull/1035
Specification
https://streams.spec.whatwg.org/#rs-default-controller-class-definitionAPI spec
YesSummary
The Streams APIs provide ubiquitous, interoperable primitives for creating, composing, and consuming streams of data. We will expose the ReadableStreamDefaultController interface on the global object, as with the other ReadableStream-related classes. This will align Blink with the current version of the Streams API Standard and consensus among the developer community. See https://github.com/whatwg/streams/issues/963.
Blink component
Blink>Network>StreamsAPITAG review
There is no TAG review for this since: - It is a tiny change to the interface
- It does not expose any new functionality
- It is already possible to call the ReadableStreamDefaultController constructor explicitly
Gecko: No signal Jason Orendorff (@jorendorff) reviewed the original PR and gave positive feedback.
WebKit: No signal
Web developers: No signals
TAG review status
Not applicableRisks
Interoperability and Compatibility
Low risk because the Streams API spec has already been standardised for a long time (since around 2014).
Gecko: No signal Jason Orendorff (@jorendorff) reviewed the original PR and gave positive feedback.
WebKit: No signal
Web developers: No signals
Ergonomics
This will move us in line with the standard behaviour for WebIDL-defined classes that are part of the web platform. See https://heycam.github.io/webidl/#NoInterfaceObject and https://heycam.github.io/webidl/#Exposed. This should reduce developer surprise.
Activation
Developers can use this feature immediately, as it does not change the behaviour of existing code. The feature can be polyfilled with one line of JavaScript: new ReadableStream({start(controller) {self.ReadableStreamDefaultController = controller.constructor; }});
Debuggability
No special support needed.
Is this feature fully tested by web-platform-tests?
YesLink to entry on the Chrome Platform Status
https://chromestatus.com/feature/5711333280448512
yo...@yoav.ws
Dec 10, 2020, 3:12:11 AM12/10/20
to blink-dev, Nidhi Jaju, Adam Rice
On Tuesday, December 8, 2020 at 10:10:59 AM UTC+1 Nidhi Jaju wrote:
Could you provide an inline explanation of what the feature is, what it looks like and how developers are supposed to use it?
Nidhi Jaju
Dec 10, 2020, 10:00:01 PM12/10/20
to yo...@yoav.ws, blink-dev, Adam Rice
Hi Yoav,
The feature is essentially just exposing the ReadableStreamDefaultController on the global object. This means that evaluating 'ReadableStreamDefaultController' in window goes from false to true. Exposing it does not expose any new functionality, so developers are not really affected in any way.
Currently, developers need to write:
new ReadableStream({start(controller) { self.ReadableStreamDefaultController = controller.constructor; }});
to call the ReadableStreamDefaultController constructor.
However, most do not use this anyway, except for maybe in web platform tests, or if they want to wrap the methods for debugging purposes for example. By exposing the interface globally, there is no need to explicitly write this one line of Javascript code anymore.
I've also added this information to the 'Motivation' section to the ChromeStatus entry, so hopefully that helps provide some more clarity/context. Thank you!
However, most do not use this anyway, except for maybe in web platform tests, or if they want to wrap the methods for debugging purposes for example. By exposing the interface globally, there is no need to explicitly write this one line of Javascript code anymore.
I've also added this information to the 'Motivation' section to the ChromeStatus entry, so hopefully that helps provide some more clarity/context. Thank you!
Best regards,
Nidhi
Yoav Weiss
Dec 15, 2020, 1:51:12 AM12/15/20
to Nidhi Jaju, blink-dev, Adam Rice
LGTM1
On Fri, Dec 11, 2020 at 3:59 AM Nidhi Jaju <nidh...@google.com> wrote:
Hi Yoav,The feature is essentially just exposing the ReadableStreamDefaultController on the global object. This means that evaluating 'ReadableStreamDefaultController' in window goes from false to true. Exposing it does not expose any new functionality, so developers are not really affected in any way.
Currently, developers need to write:
new ReadableStream({start(controller) { self.ReadableStreamDefaultController = controller.constructor; }});
to call the ReadableStreamDefaultController constructor.
However, most do not use this anyway, except for maybe in web platform tests, or if they want to wrap the methods for debugging purposes for example. By exposing the interface globally, there is no need to explicitly write this one line of Javascript code anymore.
I've also added this information to the 'Motivation' section to the ChromeStatus entry, so hopefully that helps provide some more clarity/context. Thank you!
OK, so this is just aligning our behavior to the spec. Got it! :)
TAMURA, Kent
Dec 15, 2020, 2:33:44 AM12/15/20
to Yoav Weiss, Nidhi Jaju, blink-dev, Adam Rice
LGTM2
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TAMURA Kent
Software Engineer, Google
Software Engineer, Google
Daniel Bratell
Dec 15, 2020, 4:32:26 AM12/15/20
to TAMURA, Kent, Yoav Weiss, Nidhi Jaju, blink-dev, Adam Rice
LGTM3
/Daniel
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