Please I need help on why the alert gives a value of 1

Question

https://code.sololearn.com/W66pgA5EU50L/?ref=app

Answer 1

because you got the length of a single char:
str = "Hello"
str[str.length-1] = str[3] = "o"
so, str[str.length-1].length = 1

Answer 2

Shazzar Not exactly sure.
What r u wanting it to say?

Answer 3

Thanks visph it is now clear