how is slice() working here?

Question

var str = 'i love sololearn!';
var x = -5;
document.write(str.slice(--x));
//output:learn

Answer 1

The slice() method extracts a part of the string.
So, we have the string "I love sololearn!"
x = -5.
=> --x = -1-5 = -6
When we give a negative integer as argument in the slice() method, it starts extracting from the end.
Hence it extracts 6 characters from " ! " to " l ".
Therefore, the program outputs -
learn!

NOTE - The output is " learn! " and not " learn " (note the ! ). You did some mistake in writing the question. ☺️

Hope it helps!

Answer 2

Note that x=-6, so...

i love solo l e a r n !
6 5 4 3 2 1
Look tha from "!" to "l" is exactaly 6 caracteres.