refactor: replace deprecated String.prototype.substr()

[CommanderRoot]

String.prototype.substr() is deprecated so we replace it with String.prototype.slice() which works similarily but isn't deprecated.
.substr() probably isn't going away anytime soon but the change is trivial so it doesn't hurt to do it.

[Tyriar]

Thanks, this is a good change but I'd prefer substring as it feels more natural on strings over slice.

[CommanderRoot]

The current codebase has more slice() usage than substring(). Also generally slice() is a bit faster than substring() and about the same as substr(). Slice is also bit shorter which means it the code is smaller.
If you still want to rather use substring() I can change it hower, your repo, your rules.

[Tyriar]

Think you've convinced me 🙂 Thanks!