Palindrome Javascript 2

palindrome.js

function isPalindrome(str) {
  var half = Math.round(str.length / 2);
  var start = 0;
  var end = str.length - 1;
  var palindrome = true;
  var SPACE = 32;
  var COMMA = 44;
  var startSpace, endSpace;

  while (half && palindrome) {
    startSpace = str.charCodeAt(start) === SPACE || str.charCodeAt(start) === COMMA;
    endSpace = str.charCodeAt(end) === SPACE ||  str.charCodeAt(end) === COMMA;

    if (str[start] == str[end]) {
      start++;
      end--;
    } else if (startSpace || endSpace) {
      startSpace && start++;
      endSpace && end--;
    } else {
      palindrome = false;
    }

    half--;
  }

  return palindrome;
}