How to remove irregular whitespace EMSP using javascript

I have problem where my script allow irregular whitespace EMSP eventhough I created regex that only allow alphanumerics. My code :

var modemID = source.u_modem_id.toString();
var modID = modemID.trim();
var regex = /^[a-zA-Z0-9]*$/;

if (!modID.match(regex)) {
   log.error('Invalid Modem ID. Only numbers and characters are allowed - ');
   ignore = true;
}

This is sample Modem ID with irregular whitespace

enter image description here

How to rid of it?

Im expecting getting error if Modem ID have irregular whitespace and need script to remove it.