Regex to Match only language chars (all language)?

I need to restrict users input only to alpha numeric chars.

If it was only in English It would be easy $[a-z]^/i

But I need to do it global, e.g. for every language. Is there a sequential Unicode range that include all "chars" ? If not, how can I do it?

p.s. I saw this answer but the answer was for python.