JSFiddle - React, Tailwind, and code Playground

by Kai Wang

JavaScript

function convert(s, num) {
const n = num-1;
  let rv = "";
  for (let i = 2 * n; i >= n; i--) {
    rv += test(s, n, i)
  }
  return rv
}

function test(s, n, k) {
  let rv = "";
  for (let i = 0; i < s.length; i++) {
    if (i % (2 * n) == k || i % (2 * n ) == (2 * n - k)) {
      rv += s.charAt(i)
    }
  }
  return rv
}
var string = "PAYPALISHIRING";
var a = convert(string,3);
console.log(a)