getFirstNonAsciiCharIndex function
Returns, if any, the index of the first non-ASCII character in the string. If the string is either empty or all-ASCII, null is returned.
Implementation
int? getFirstNonAsciiCharIndex(String string) {
for (var i = 0; i < string.length; i++) {
final c = string.codeUnitAt(i);
if (!isValidAsciiChar(c)) {
return i;
}
}
return null;
}