Does anyone know how to list all files in an specific directory?
I can't seem to find an answer with the same content. In .Net it was like Directory.GetFiles(dir), I don't know what is the counterpart of that in Typescript.
Client-side javascript (browser) does not have access to file system. On server the way depends on what technology you use.
From your description is not obvious where you need to access file system. Please update your question with additional information.
Edit:
You cannot list directory with Angular. The only option is to use HTTP request to get content of file. The file must contain generated JSON (for example) with all filepaths. So you need server which will generate the file for you. Angular is designed to work with provided data from APIs, not for using file system.