Answers for "js how to take first element of string and put it on the end of same string"

how to get the first character of a string in javascript

let str = 'John Wick'
let firstChar = str.charAt(0) 
console.log(firstChar); // "J"

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"