In both python and JavaScript we can access the char of string with bracket:

in python

s = "abc"
s[0]
# it returns 'a'

in JavaScript

s = "abc"
s[0]
// it returns 'a'

But if we use the index -1 to get the last char

in python

s[-1]
# it returns 'c'

in JavaScript

s[-1]
# it returns undefined

Fortunately, we can simply use s[s.length - 1].