toNullableString method
Implementation
String? toNullableString() {
if (isUndefinedOrNull) return null;
if (isA<JSString>()) return (this as JSString).toDart;
if (isA<JSNumber>()) return (this as JSNumber).toDartDouble.toString();
if (isA<JSBoolean>()) return (this as JSBoolean).toDart.toString();
return null;
}