String incrementer.js

/*
Description:
Your job is to write a function which increments a string, to create a new string. If the string already ends with a number, the number should be incremented by 1. If the string does not end with a number the number 1 should be appended to the new string.

Examples:

foo -> foo1

foobar23 -> foobar24

foo0042 -> foo0043

foo9 -> foo10

foo099 -> foo100

Attention: If the number has leading zeros the amount of digits should be considered.
*/
let incrementString = str => str.replace(/([0-8]|\d?9+)?$/, (e) => e ? + e + 1 : 1)