Why you cannot replace javascript in the browser with swift? or Why you can't add swift in the browser and use it to detect and catch browser event?

Thank you for your answer but, I'm sorry, doesn't solve the problem that I wrote. What are you speaking about is what I do to try open a CSS file. but doesn't work. And I don't know why. If I create a new type (e.g. webcodeproj) I can open because the file is selectable in open dialog panel. but with css, that it should be a knowable type of file, I can't select the file. Why? Can you explain in more detail what I have to do to can open and write files like html, css and javascript?

Unfortunally I've the same problem with Simulator of Xcode 15 and Xcode 15.2 Beta