thank you :)

Did anyone had the same problem? the script seems to work on codepen but when I put it here everything goes 'undefined' I've added a line to catch the console log and the results are the log is the same as "expected" by codewars.. not sure what I should do. :)

Log
true
Expected: 'true', instead got: 'undefined'

Log
false
same chars may not be adjacent - Expected: 'false', instead got: 'undefined'

Log
false
same chars may not be same case - Expected: 'false', instead got: 'undefined'

Log
false
Expected: 'false', instead got: 'undefined'

Log
true
an empty string is a valid isogram - Expected: 'true', instead got: 'undefined'