thx man for your reply, I was stupid too with this 26 symbols

there is no need to get katakana alphabet set
if u do the others proply the katakana one should be ok
check the rest code if theres some mistake

ahh thx dude ,this shit had drive me .I was so stupid and thought there were only 26 chars in the abc, so I just typed number 26 in my code ,after seeing ur solution I changed my 26 to abc.longth and it passed .:)

im just simply adding the index of PW str am I doing it wrong ?

I am not sure if I understand you, but I believe this is your problem.
The katakana character set used by this kata is not a consistent sequence of codepoints, and you need to use actual definition of the alphabet to check what a character shifted for x positions is. You cannot just convert a charater to its code point, add x to it, and convert it back to a character - this wont work. For the Latin alfabet, it's true that 'c' + 3 == 'f', but it's a coincidence which does not hapen for the katakana alphabet in this kata.

is that means PW is カタカナ and is should decode or encode カタカナ to タモタワ?

Yes, you can log stuff to console to see this better.

coz theres no way Japanese used the abc just like English right?

It should be handled the same way, I think.

all tests passed except this thit
Password of 'カタカナ'
expected 'タコタナ' to equal 'タモタワ'
what the heck is the shit .
I tried just return the str
it shows Password of 'カタカナ'
expected 'カタカナ' to equal 'タモタワ'
is that means PW is カタカナ and is should decode or encode カタカナ to タモタワ?
and btw should I do it in the katakana to tamotawa way i mean k convert to t something like that or do it in the Japanese char list way ?
coz theres no way Japanese used the abc just like English right?
im just simply adding the index of PW str am I doing it wrong ? since others all passed I just cant figure it out