SimplePalindrom.js

function mostSignificantDigit (n) {
    var maxNumber = Math.pow(10, n) - 1;
  return maxNumber;
}
function _minNumber (n) {
    var minNumber = 1 + Math.pow(10, n - 1);
  return minNumber;
}
function isPrimary (i) {
  for ( var j = 2; j < Math.sqrt(i); j++) {
    if (i % j === 0) {
      return false;
    }
  }
 return true;
}
function isPalindrom (number) {
    var arr = ("" + number).split("");
    for (var i = 1; i <= (arr.length / 2); i++) {
      if (arr[i-1] !== arr[arr.length - i]) {
        return false;
    }
  }
  return true;
}
function checkPrimaryNumber(nMax, nMin) {
    for ( var i = nMax; i > nMin; i-- ) {
        if(isPrimary(i)) {
        if (isPalindrom(i)) {
          return i;
      };
    }
    
  }
  return -1;
}
function checkPrimaryPalindrom (number) {
    var maxNumber = mostSignificantDigit(number);
  var minNumber = _minNumber(number)
  return checkPrimaryNumber(maxNumber, minNumber);
 }
console.log(checkPrimaryPalindrom(1));