substring in javascript from end code example

Example 1: js get first 3 characters of string

const string = "0123456789";
console.log(string.slice(0, 2)); // "01"
console.log(string.slice(0, 8)); // "01234567"
console.log(string.slice(3, 7)); // "3456"

Example 2: str.substring if 2 letters

public String firstTwo(String str) {
    return str.length() < 2 ? str : str.substring(0, 2);
}