How to check if input is a real character when a keyboard event is triggered in JavaScript/TypeScript?

I registered a keyboard listener in JS for my image gallery view. When the user inputs a character I want to jump to the first item whose name matches the first character of the typed character.

I can of course just check for [a-zA-Z0-9-_…] but there are many other characters that the user could type, e.g. through a Japanese or Chinese keyboard.

Is there a way to test if an input is a real text character?