Intent to Ship: JavaScript Promise Integration

[Chromestatus]

Contact emails

f...@chromium.org, thib...@chromium.org, ire...@chromium.org

Explainer

https://github.com/WebAssembly/js-promise-integration/blob/main/proposals/js-promise-integration/Overview.md

Specification

https://github.com/WebAssembly/js-promise-integration/blob/main/proposals/js-promise-integration/Overview.md

Design docs

https://docs.google.com/document/d/16Us-pyte2-9DECJDfGm5tnUpfngJJOc8jbj54HMqE9Y/edit#heading=h.n1atlriavj6v

Summary

JavaScript Promise Integration (JSPI) is an API that allows WebAssembly applications to integrate with JavaScript Promises. It allows a WebAssembly program to act as the generator of a Promise, and it allows the WebAssembly program to interact with Promise-bearing APIs. In particular, when an application uses JSPI to call a Promise-bearing (JavaScript) API, the WebAssembly code is suspended; and the original caller to the WebAssembly program is given a Promise that will be fulfilled when the WebAssembly program finally completes. JSPI is described in more detail in https://github.com/WebAssembly/js-promise-integration which is part of the W3C WebAssembly standards track. See also https://github.com/WebAssembly/stack-switching and https://github.com/WebAssembly/meetings/tree/main/stack.

Blink component

Blink>JavaScript>WebAssembly

Search tags

stack switching, Promise, JSPI

TAG review

https://github.com/w3ctag/design-reviews/issues/809 Review was declined, deferring to W3C WebAssembly CG

TAG review status

Issues addressed

Origin Trial Name

WebAssembly JavaScript Promise Integration

Chromium Trial Name

WebAssemblyJSPromiseIntegration

Origin Trial documentation link

https://github.com/WebAssembly/js-promise-integration

WebFeature UseCounter name

kV8WasmJavaScriptPromiseIntegration

Risks

Interoperability and Compatibility

This spec is backed by a standardization effort. We do not plan to ship the JSPI until it has been standardized by the W3C Wasm WG. However, post standardization, we will depend on all browsers implementing the standard.

Gecko: Positive (https://bugzilla.mozilla.org/show_bug.cgi?id=1850627) Mozilla have started their own imlementation

WebKit: No signal (https://github.com/WebKit/standards-positions/issues/422)

Web developers: No signals

Other signals:

Activation

Making use of JSPI requires some changes by WebAssembly-based developers (no impact on JavaScript developers). Depending on their toolchain usage a developer will need to modify their code. For Emscripten users, this is likely to be minimal as support for JSPI exists in Emscripten.

Security

1. Control flow integrity. 2. Ensuring that JavaScript programs cannot suspend via JSPI. 3. Ensuring that heap sandbox escapes are not possible.

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

No.

Debuggability

Developers can piggyback on existing DevTools support for Promises to help with debugging JSPI applications. In particular the existing mechanisms for constructing extended stack traces from so-called Promise chains will also include stack traces from JSPI applications.

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

Yes

Is this feature fully tested by web-platform-tests?

Yes

https://wpt.fyi/results/wasm/jsapi/jspi

Flag name on about://flags

enable-experimental-webassembly-stack-switching

Finch feature name

None

Non-finch justification

None

Rollout plan

Will ship enabled for all users

Requires code in //chrome?

False

Tracking bug

https://bugs.chromium.org/p/v8/issues/detail?id=12191&q=owner%3Ame&can=2

Measurement

https://chromestatus.com/metrics/feature/timeline/popularity/4760

Availability expectation

JSPI will be available on Chrome (including Edge) and on FireFox at launch. No specific indication about availability on Safari.

Adoption expectation

1. We expect that JSPI will be used by both 1P and 3P partners within a few months of launch.

Adoption plan

1. There has been an origin trial running for one year. This OT has > 300 registrants at time of writing. 2. We will be publishing V8.dev blog posts both about the feature (see https://v8.dev/blog/jspi-newapi) and its implementation. We believe that this will further increase awareness of JSPI. 3. We will also benefit from awareness of WebAssembly and the W3C wasm CG.

Non-OSS dependencies

Does the feature depend on any code or APIs outside the Chromium open source repository and its open-source dependencies to function?

no.

Estimated milestones

Shipping on desktop	137
Origin trial desktop first	123
Origin trial desktop last	131
Origin trial extension 1 end milestone	131
Origin trial extension 2 end milestone	133
Origin trial extension 3 end milestone	136
DevTrial on desktop	109
Shipping on Android	137
Origin trial Android first	123
Origin trial Android last	131
Shipping on WebView	137
Origin trial WebView first	123
Origin trial WebView last	131

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

No spec changes anticipated. JSPI is part of a W3C standards process (see https://github.com/WebAssembly). We plan to ship after this spec reaches 'stage 4' which represents a completed specification.

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5674874568704000?gate=5851957764292608

Links to previous Intent discussions

Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAAdKk6BGFseZ6pBO2qEW_xeovVw1_guVq26rcNM1nWY442Y5Ng%40mail.gmail.com
Intent to Experiment: https://groups.google.com/a/chromium.org/g/blink-dev/c/Fu79zrp7MoE
Intent to Extend Experiment 1: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CALi9WK-JJNTYSeNdSuai827Qg5%3D2vZo-emYP2z-5vJOfE%2B8Nng%40mail.gmail.com
Intent to Extend Experiment 2: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/67103777.2b0a0220.137ef7.0e4c.GAE%40google.com
Intent to Extend Experiment 3: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAE65UWDsoPqTePz3S42YsV2_Wr3OGL6yY2YdsS6oOYw3Rh8%2Bww%40mail.gmail.com

This intent message was generated by Chrome Platform Status.

[Philip Jägenstedt]

LGTM1, very exciting to see this ship!

There are some apparent failures in https://wpt.fyi/results/wasm/jsapi/jspi, but this seems to be because of https://github.com/web-platform-tests/wpt.fyi/issues/4216, not real failures.

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[Chris Harrelson]

LGTM2

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAARdPYcnDkdpAWDeod8YB853RKTDD6G%2BccXbfG4eWwCpsx%3DLyw%40mail.gmail.com.

[Mike Taylor]

LGTM3

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw8BHA-bsxy50tGX4Krt1SVwt7%2BrADBM4RWbhHXYiHUO8w%40mail.gmail.com.