You have to check if the digits are sequential, not if they are ordered. Made the same mistake and had to think about some time to get it.

I don't know where you are from, but where I'm from, neither 7540 nor 1590 have sequential digits! ;-)

It's not just incrementing or decrementing, it's incrementing or decrementing sequential digits. So, 1234 is valid, but 1357 isn't.

Good Luck!

In this kata, closing brace may be ")", "}", or "]" . . .

Hint: you can use console.log() to see the input string for each test.

closing brace without opening one before.