Filter non-Alpha characters for multiple languages

Question

I want to write a regex to remove all non alpha characters, as follows:

björn -> björn
Barry's -> barrys
Who? -> who
Cibé? -> cibé
I'd -> id
ice-cream -> icecream
No!!! -> no
[{brackets}] -> brackets
~inv3rse -> invrse

and to convert all characters to their lowercase versions. How do I do this for all languages or at least for European languages using the Latin script?

Answer 1

str.toLowerCase().replace(/[^a-z]/gi,'');

this will convert everything to lowercase, then replace everything that isn't an alphabetic character (a-z) to the empty string, essentially removing them. in order to keep certain other characters (like e with an accent mark) just add that symbol to the regex.