[browser] Marshalling support float[], Span<float> and ArraySegment<float> #123642

ArcadeMode · 2026-01-26T21:37:21Z

Implementation is functional for CoreCLR and Mono. Added import and export tests to demonstrate.

How do I go about updating the docs? (and which version might see these changes for that matter, net10/11?)

pavelsavara · 2026-01-27T07:56:00Z

@ArcadeMode feel free to ping me on your PRs, so that I can label it properly.

ArcadeMode · 2026-01-27T23:01:29Z

@pavelsavara to verify that i am following contribution guidelines: I have already changed and implemented an API change, is it okay to ask for API review in PR like this?

i.e. would a similar approach suffice for #97381 or should this be done through the issue or otherwise?

Copilot

Pull request overview

This pull request adds marshaling support for float[], Span<float>, and ArraySegment<float> between C# and JavaScript in the browser WASM interop layer, addressing issue #97380.

Changes:

Added MemoryViewType.Single enum value and corresponding Float32Array handling
Implemented C# marshaling methods for float arrays, spans, and array segments
Updated TypeScript marshaling code to handle Single type in both native and mono implementations
Added comprehensive test coverage for JSImport and JSExport scenarios with float types
Updated code generator to recognize Single type patterns

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/native/libs/System.Runtime.InteropServices.JavaScript.Native/interop/marshaled-types.ts	Added MemoryViewType.Single enum and Float32Array view creation
src/native/libs/System.Runtime.InteropServices.JavaScript.Native/interop/marshal.ts	Added Single to elementSizeMap with 4-byte size
src/native/libs/System.Runtime.InteropServices.JavaScript.Native/interop/marshal-to-js.ts	Implemented Single type marshaling for arrays, spans, and array segments
src/native/libs/System.Runtime.InteropServices.JavaScript.Native/interop/marshal-to-cs.ts	Implemented Single type unmarshaling and view type checking
src/mono/browser/runtime/marshal.ts	Added Single to array_element_size function and MemoryViewType enum, refactored to if-else chains
src/mono/browser/runtime/marshal-to-js.ts	Implemented Single type marshaling for arrays, spans, and array segments in mono runtime
src/mono/browser/runtime/marshal-to-cs.ts	Implemented Single type unmarshaling and view type checking in mono runtime
src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.Single.cs	Added ToJS/ToManaged methods for float[], Span, and ArraySegment
src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.Object.cs	Added float[] handling in ToJS method for object parameters
src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/JSMarshalerType.cs	Updated validation methods to accept Single type in arrays, spans, and segments; removed extraneous blank line
src/libraries/System.Runtime.InteropServices.JavaScript/ref/System.Runtime.InteropServices.JavaScript.cs	Added public API surface for float[], Span, and ArraySegment marshaling
src/libraries/System.Runtime.InteropServices.JavaScript/gen/JSImportGenerator/JSGeneratorFactory.cs	Added generator patterns for Single type arrays, spans, and array segments
src/libraries/System.Runtime.InteropServices.JavaScript/tests/.../JavaScriptTestHelper.cs	Added test helper methods for Single type JSImport and JSExport scenarios
src/libraries/System.Runtime.InteropServices.JavaScript/tests/.../JSInteropTestBase.cs	Added MarshalSingleArrayCases test data
src/libraries/System.Runtime.InteropServices.JavaScript/tests/.../JSImportTest.cs	Added comprehensive tests for float arrays, spans, and array segments; improved variable naming in Double/Int32 tests
src/libraries/System.Runtime.InteropServices.JavaScript/tests/.../JSExportTest.cs	Added JSExport tests for Span and ArraySegment

...cript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.Object.cs

pavelsavara · 2026-01-28T08:07:38Z

is it okay to ask for API review in PR like this?

The process is described here https://github.com/dotnet/runtime/blob/main/docs/project/api-review-process.md

You need to create dedicated issue according to the issue template for API suggestion.

You can also look at successfully approved APIs

ArcadeMode · 2026-01-28T08:51:19Z

is it okay to ask for API review in PR like this?

The process is described here https://github.com/dotnet/runtime/blob/main/docs/project/api-review-process.md

You need to create dedicated issue according to the issue template for API suggestion.

You can also look at successfully approved APIs

Thanks for the pointers. I have created #123706 with the proposal

pavelsavara · 2026-01-28T10:50:41Z

test for JS Array values of wrong type or JS number (double) above float.max would be great

ArcadeMode · 2026-01-28T21:22:45Z

test for JS Array values of wrong type or JS number (double) above float.max would be great

I have created #123731 to resolve issues with type assertions for array elements. Here I would only end up adding demonstration that the float would overflow (as demonstrated for int32). I hope I can address that issue separately.

pavelsavara · 2026-01-29T09:58:20Z

The code looks good. I added NO-MERGE label until we pass the API review.

Copilot

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 1 comment.

Copilot · 2026-01-29T17:14:58Z

...teropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSImportTest.cs

+            var expectedBytes = stackalloc float[] { 0, 1, -1, float.Pi, 42, float.MaxValue, float.MinValue, float.NaN, float.PositiveInfinity, float.NegativeInfinity };
+            Span<float> expected = new Span<float>(expectedBytes, 10);
+            Assert.True(Unsafe.AsPointer(ref expected.GetPinnableReference()) == expectedBytes);


The variable name expectedBytes is misleading since it contains float data, not bytes. For consistency with other test methods in this file (e.g., expectedInts on line 558, expectedDoubles on line 572, and expectedFloats on line 586), this variable should be renamed to expectedFloats.

Suggested change

var expectedBytes = stackalloc float[] { 0, 1, -1, float.Pi, 42, float.MaxValue, float.MinValue, float.NaN, float.PositiveInfinity, float.NegativeInfinity };

Span<float> expected = new Span<float>(expectedBytes, 10);

Assert.True(Unsafe.AsPointer(ref expected.GetPinnableReference()) == expectedBytes);

var expectedFloats = stackalloc float[] { 0, 1, -1, float.Pi, 42, float.MaxValue, float.MinValue, float.NaN, float.PositiveInfinity, float.NegativeInfinity };

Span<float> expected = new Span<float>(expectedFloats, 10);

Assert.True(Unsafe.AsPointer(ref expected.GetPinnableReference()) == expectedFloats);

pavelsavara · 2026-01-29T20:20:23Z

...vices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.cs

        [return: JSMarshalAs<JSType.Number>]
        internal static partial double? store_DoubleArray([JSMarshalAs<JSType.Array<JSType.Number>>] double[]? value, [JSMarshalAs<JSType.Number>] int index);

+        [JSImport("echo1", "JavaScriptTestHelper")]


Could you please add few signatures without JSMarshalAs annotations. They should work fine too.

pavelsavara · 2026-01-29T20:22:54Z

Please add few float signatures so that the generated code appears in src/libraries/System.Runtime.InteropServices.JavaScript/tests/JSImportGenerator.UnitTest/Compiles.cs

ArcadeMode added 5 commits January 26, 2026 03:53

update codegen

841a588

update interop js for coreclr

3f215ae

add span test

c5d8fb5

float array and arraysegment cs-js and cs-js marshalling + tests

66c2125

Merge remote-tracking branch 'origin/main' into float-array-span-segment

c7e745a

github-actions bot added the area-System.Runtime.InteropServices.JavaScript label Jan 26, 2026

dotnet-policy-service bot added the community-contribution Indicates that the PR has been added by a community member label Jan 26, 2026

pavelsavara added arch-wasm WebAssembly architecture os-browser Browser variant of arch-wasm labels Jan 27, 2026

pavelsavara self-assigned this Jan 27, 2026

ArcadeMode added 4 commits January 27, 2026 20:36

add export tests

f07af2d

update ref

e349ba7

impl mono side

ca03151

pointer offset 4bytes

002250e

ArcadeMode marked this pull request as ready for review January 27, 2026 22:55

ArcadeMode requested review from lewing and pavelsavara as code owners January 27, 2026 22:55

Copilot AI review requested due to automatic review settings January 27, 2026 22:55

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...cript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.Object.cs Show resolved Hide resolved

ArcadeMode added 2 commits January 28, 2026 00:57

add float handling to ToManaged

0f7ede3

alloc free elem size

561786c

build-analysis bot mentioned this pull request Jan 28, 2026

slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883

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pavelsavara mentioned this pull request Jan 28, 2026

[API Proposal]: JavaScript marshalling support float[], Span<float> and ArraySegment<float> #123706

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pavelsavara added this to the 11.0.0 milestone Jan 28, 2026

pavelsavara added the NO-MERGE The PR is not ready for merge yet (see discussion for detailed reasons) label Jan 29, 2026

Copilot AI review requested due to automatic review settings January 29, 2026 17:04

Merge branch 'main' into float-array-span-segment

3189a99

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iOS.Device test WorkItemExecutions #122874

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[browser] Marshalling support float[], Span<float> and ArraySegment<float> #123642

[browser] Marshalling support float[], Span<float> and ArraySegment<float> #123642

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