almost_palindrome.js

function is_onestep_palidrome(str) {
  function is_palindrome(str_) {
    return str_ == str_.split('').reverse().join('');
  }

  function swapStr(str, first, last) {
    if (first == last) {
      return str;
    }

    if (last < first) {
      var temp = last;
      last = first;
      first = temp;
    }

    if (first >= str.length) {
      return str;

    }
    return str.substring(0, first) +
      str[last] +

      str.substring(first + 1, last) +

      str[first] +
      str.substring(last + 1);
  }



  var diff = [];
  var start = 0;
  var end = str.length - 1;

  while (start < end) {
    if (str.charAt(start) != str.charAt(end)) {
      diff.push(start);
    }
    start++;
    end--;
  }
  if (diff.length === 0) {
    print('YES');
    return;
  }

  if (diff.length == 1) {
    if (is_palindrome(swapStr(str, diff[0], Math.floor(str.length / 2))) ||
      is_palindrome(swapStr(str, str.length - 1 - diff[0], Math.floor(str.length / 2)))
    ) {

      print('YES');
    } else {
      print('NO');

    }
    return;
  }

  if (diff.length == 2) {
    if (is_palindrome(swapStr(str, diff[0], diff[1])) ||
      is_palindrome(swapStr(str, diff[0], str.length - 1 - diff[1])) ||
      is_palindrome(swapStr(str, diff[1], str.length - 1 - diff[0]))

    ) {
      print('YES');

    } else {
      print('NO');

    }
    return;
  }

  print('NO');

}

is_onestep_palidrome(readline().trim())