[Web API type definition issue] `MediaSourceHandle` results in `any`

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#2,316 opened on Dec 24, 2025 3 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty: 3/5
Estimated time: 1-2 days
Newbie friendliness: 45/100

Issue type: Bug
Clarity: Mostly clear
Activity status: Stale
Tech stack: typescript
Domain: tooling

Research direction

Start by tracing how the generator represents MediaSourceHandle and produces its declaration, then inspect the generated type's relationship to Transferable. Done means the generated MediaSourceHandle definition no longer behaves as an empty interface equivalent to any, so Transferable does not accept arbitrary any values.

Written by the indexing model from the issue text.

Description

lib.d.ts bug

Summary

MediaSourceHandle results in any making Transferable wrong

Expected vs. Actual Behavior

Currently the type generation for MediaSourceHandle results in

/**
 * The **`MediaSourceHandle`** interface of the Media Source Extensions API is a proxy for a MediaSource that can be transferred from a dedicated worker back to the main thread and attached to a media element via its HTMLMediaElement.srcObject property.
 *
 * [MDN Reference](https://developer.mozilla.org/docs/Web/API/MediaSourceHandle)
 */
interface MediaSourceHandle {
}

declare var MediaSourceHandle: {
    prototype: MediaSourceHandle;
    new(): MediaSourceHandle;
};

And empty interfaces are known for being equal to any in TS, so this makes Transferable accept any types, which is wrong.

Playground Link

No response

Browser Support

This API is supported in at least two major browser engines (not two Chromium-based browsers).

Have Tried The Latest Releases

This issue applies to the latest release of TypeScript.
This issue applies to the latest release of @types/web.

Additional Context

Currently using latest typescript 5.9.3

My workaround for now is using this definition.

interface MediaSourceHandle {
  __dummy__: never
}

Dominant language: TypeScript
Stars: 740
Forks: 474
Avg merge: 2d 8h
Merged PRs (30d): 15

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