My friend was asking can Html, Css , Typescript and C# be use in web/app development together....
PS. Who can answer this and vote...

But why would you want to?

Yes, use webpack to transpile Typescript into javascript.

I think hes havin a stroke tbh

Blazor is the answer.

And Bridge.Net is as well

I‘m doing it currently at work. C# backend with .Net core and an Angular frontend.

I'm not sure if you're genuinely seeking an answer, or you're expressing your frustration at the obvious answer

@jAsE 420 Blazor

HTML, CSS, TS in front end and C# In back end. Its probably not even uncommon.

@AlgoRythm ah frontend and backend. I assumed all frontend. In that case it is indeed not so uncommon. A lot of people use it..

Because OPs friend asked for working together and every backend and frontend language works together if you want to my assumption went to all frontend.

In that case its not common at all and a valid question. And the answer would be Blazor (C# as WebAssembly) or Bridge.Net (C# transpiled to javascript)
Both work great in combination with javascript and thus typescript.