IMO, I think that this logic should be implemented on the client side.

In the LSP spec, a diagnostic can have a code property:

export interface Diagnostic {
	/**
	 * The diagnostic's code, which might appear in the user interface.
	 */
	code?: integer | string;
} 

Why?

It makes more sense to filtering diagnostics by the code on the client,
because than all servers do not have to implement their own way of filtering diagnostics by code. (keep in mind that there are less clients, than servers)

Valid point. I guess I will drop it unless someone else some good arguments for having it.

I'll go with that after all.

Asking all clients to support that takes quite some effort and convincing and it's not even clear if client authors would want to implement that.

And fixing will close a bunch of issues. :)

It's not even clear if client authors would want to implement that.

Yes, it is true that it is not specified in the spec.

Clients already implemented the ability to filter out diagnostics by severity to only show errors and warnings, and hide info, and hints.
That is also not defined in the spec, but yet it made sense for the client to do it.

I do not have anything again this PR,
if this fixes a lot of issues now, why not merge it? :)

Yes, it is true that it is not specified in the spec.

I did not make such argument. :)

if this fixes a lot of issues now, why not merge it? :)

Well, I guess only this one #142 :P

But still, it's low effort, hopefully no maintenance feature so I don't mind.

Quite a lot people are suffering from microsoft/vscode#47299 I think

Since that thread is locked, can I link it here to give some hits for folks over there?
Seems that what locked is locked :(

n00b question @rchl: where exactly can I add this setting? I've tried my projects tsconfig.json, but that wasn't it. I use coc-tsserver, but I didn't see the option there either.

@jacobchrismarsh coc-tsserver doesn't use this package.
Instead it has ots own implementation for communicating with the tsserver.

@jacobchrismarsh coc-tsserver doesn't use this package. Instead it has ots own implementation for communicating with the tsserver.

Ah, that makes sense. Alright then! Thanks, for the info @predragnikolic