Error `ts(2339)` happening for plain JavaScript files

[DervishD]

Issue Type: Bug

Even though I noticed this problem recently, according to some sources I've searched this has been happening since 2018, at least:
https://stackoverflow.com/questions/51069070/removing-ts-errors-from-js-files-in-vs-code
https://stackoverflow.com/questions/42632215/how-to-disable-typescript-warnings-in-vscode
microsoft/vscode#51378

There are more similar entries and issues, but those are good enough for illustration purposes, I think.

The usual reply to this problem is to add the following to settings.json:

"typescript.validate.enable": false,
"javascript.validate.enable": false,

Apparently, the first one is essential, the second one needed sometimes.

This is the bare minimum JavaScript file showing the problem (at least in my system):

self.example = 0;

The above code produces the warning: Property 'example' does not exist on type 'Window & typeof globalThis'.ts(2339)

I'm not using TypeScript at the moment, but I would not like to disable validation just because the TypeScript validator is checking my plain JavaScript files.

I'm not completely sure this is a bug, rather than some unintended side effect of the TypeScript extension or validator, but in my humble opinion the TypeScript validator should not be emitting this kind of warnings.

Is there any reason why TypeScript validator is trying to validate plain JavaScript files? Any way of disabling this or is the intended behaviour?

Thanks in advance.

VS Code version: Code 1.61.1 (c13f1abb110fc756f9b3a6f16670df9cd9d4cf63, 2021-10-14T01:19:42.089Z)
OS version: Windows_NT x64 10.0.19043
Restricted Mode: No

System Info

Item	Value
CPUs	AMD Ryzen 7 3700U with Radeon Vega Mobile Gfx (8 x 2296)
GPU Status	2d_canvas: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: enabled opengl: enabled_on rasterization: enabled skia_renderer: enabled_on video_decode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	13.95GB (8.12GB free)
Process Argv	C:\Users\rauln\Desktop\trujaman --crash-reporter-id 615257f4-e02c-4d75-b713-fcc927501c9c --crash-reporter-id 615257f4-e02c-4d75-b713-fcc927501c9c --crash-reporter-id 615257f4-e02c-4d75-b713-fcc927501c9c
Screen Reader	no
VM	0%

Extensions (29)

Extension	Author (truncated)	Version
commit-message-editor	ada	0.19.1
github-markdown-preview	bie	0.1.0
markdown-checkbox	bie	0.3.2
markdown-emoji	bie	0.2.1
markdown-preview-github-styles	bie	0.2.0
insert-unicode	bru	0.13.1
vscode-eslint	dba	2.2.1
githistory	don	0.6.18
viml	dun	0.1.7
large-comments	elg	0.1.1
remotehub	Git	0.16.0
reg	ion	1.0.3
vscode-gutter-preview	kis	0.28.0
git-graph	mhu	1.30.0
vscode-language-pack-es	MS-	1.61.5
python	ms-	2021.10.1336267007
vscode-pylance	ms-	2021.10.1
jupyter	ms-	2021.9.1101343141
jupyter-keymap	ms-	1.0.0
jupyter-renderers	ms-	1.0.3
remote-wsl	ms-	0.58.2
hexeditor	ms-	1.8.2
live-server	ms-	0.2.9
trailing-spaces	sha	0.3.1
rewrap	stk	1.14.0
code-spell-checker	str	2.0.10
code-spell-checker-spanish	str	2.0.2
shell-launcher	Tyr	0.4.1
snippet	vsc	0.8.1

A/B Experiments

vsliv368cf:30146710
vsreu685:30147344
python383cf:30185419
pythonvspyt602:30300191
vspor879:30202332
vspor708:30202333
vspor363:30204092
pythonvspyt639:30300192
pythontb:30283811
pythonvspyt551:30345470
pythonptprofiler:30281270
vshan820:30294714
vstes263:30335439
pythondataviewer:30285071
pythonvsuse255:30340121
vscod805cf:30301675
pythonvspyt200:30340761
binariesv615:30325510
vsccppwt:30382697
pythonvssor306:30344512
bridge0708:30335490
pygetstartedt2:30371810
dockerwalkthru:30377721
bridge0723:30353136
pythonrunftest32:30373476
pythonf5test824:30373475
javagetstartedc:30364665
pythonvspyt187:30373474
vsqsis200cf:30381675
vsaa593cf:30376535
vssld246cf:30379912

[mjbvz]

Have you enabled type checking of your javaScript files? This doesn't happen for me with your example code unless I enable type checking

After enabling checking:

[DervishD]

Hi @mjbvz and thanks for the prompt reply.

No, I've not enabled type checking on my JavaScript files, at least not using //@ts-check pragma.

I've enabled JavaScript checking, though, using javascript.validate.enable, and when I disable that options, the warnings go away. These warnings, by the way, are not signalled by ESLint (which I use to lint my plain JavaScript files).

Here's the problem in action.

I'm starting to think that the problem may be related to the self variable instead. The code belongs to a Web Worker, and maybe the problem lies there: self is not of type Window, but WorkerGlobalScope and the validator does not know that.

So, maybe the problem has nothing to do with the TypeScript validator being used for plain JavaScript code, but with the fact that the validator does not have a way of knowing that self in that context is not a reference to the Window object.

I've found this: https://stackoverflow.com/questions/46493539/tell-vscode-that-the-file-is-a-web-worker/50823389

Any way of telling that to the validator in Web Workers?

[mjbvz]

Can you try to put together a minimal project that shows this issue? When I tested in a single JS file, I did not see this behavior

[DervishD]

I've reproduced it with a single JS file, with the following contents:

self.test = 0;

The code above is valid JS as far as I know, and is valid both if self is the Window object or if it is a WorkerGlobalScope. BUT to be honest, the warning here is legit, as test is, obviously, not an existing property on Window or WorkerGlobalScope.

I'm afraid this is the intended and correct behaviour and I was just too stupid to notice, my bad. But, is there any way of disabling this check for the affected lines? // @ts-ignore does not work, by the way.

I may be wrong here and the warning may be not legit after all, but if I had to choose, I'd bet on my stupidity for not noticing this, rather than on the warning appearing when it should.

Still, for Web Workers, the warning should read on type WorkerGlobalScope, but I think that's impossible because distinguishing between contexts for Web Worker is not obvious (at least for me).

[mjbvz]

Since I can't reproduce this issue, can you please try collecting the TS Server log so we can see what is going on:

1. Set "typescript.tsserver.log": "verbose",
2. Restart VS Code and reproduce the problem
3. In VS Code, run the TypeScript: Open TS Server log command
4. This should open a large log file called tsserver.log

⚠️Warning: The TypeScript log may include information from your workspace, including file paths and source code. If you have any concerns about posting this publicly on Github, just let me know and we can arrange something else. On our side, we only use these logs to investigate issues like this

[DervishD]

Again, thanks, @mjbvz , and here are the contents of tsserver.log. The only revealed path is my user home directory, no big deal.
tsserver.log

If you also need my settings.json or any other information, please let me know.

[mjbvz]

Thanks for the logs @DervishD! You should be able to hide the suggestion by setting "javascript.suggestionActions.enabled": false

Moving upstream to TS as I'm not sure why the suggestions is being generated in this case. Hopefully someone on the TS team may know from the logs

[DervishD]

Thanks to you, @mjbvz! Your solution works, but of course turns off ALL suggestions. Is there any way of having more granularity and control over which suggestions are turned off and where (line, block, etc.) like in other linters?

And you're welcome, getting the logs is zero effort, to be sincere. If you need any other thing from me to help investigating this issue, just ask.

THANKS!