lib.webworker.d.ts doesn't include canvas related types

[LubosD]

lib Update Request

Configuration Check

My compilation target is ES2015 and my lib is webworker, es2019.

Missing / Incorrect Definition

Canvas-related types, such as CanvasState, are not present in lib.webworker.d.ts in any of the latest releases (4.5.5, 4.6.0-beta etc.). They are only present in lib.dom.d.ts.

This prevents the use of @types/offscreencanvas in webworker sources build.

Somehow confusingly, the missing types are there in your main and release-4.6 (in lib.webworker.d.ts), but not in actual releases in NPM.

Sample Code

Installing @types/offscreencanvas and using "types": ["offscreencanvas"]. No code is needed, because this will fail on its own if webworker lib is used (instead of dom).

Build failure:

Error: node_modules/@types/offscreencanvas/index.d.ts:14:53 - error TS2304: Cannot find name 'CanvasState'.

14 interface OffscreenCanvasRenderingContext2D extends CanvasState, CanvasTransform, CanvasCompositing,
                                                       ~~~~~~~~~~~


Error: node_modules/@types/offscreencanvas/index.d.ts:14:66 - error TS2304: Cannot find name 'CanvasTransform'.

14 interface OffscreenCanvasRenderingContext2D extends CanvasState, CanvasTransform, CanvasCompositing,
                                                                    ~~~~~~~~~~~~~~~

Documentation Link

MDN specifically mentions that OffscreenCanvas is available in web workers.

[Josef-Haupt]

This really is a blocker for anyone using webworkers in combination with offscreencanvas anywhere in the code.

[jtbandes]

Maybe fixed by #51300?

[Swoorup]

Is there a workaround for this?

[jakebailey]

This was fixed in #51300, yes.