Javascript String palindrome()

String.prototype.palindrome = function () {
    var word = this;
    console.info(word.match(/[a-zA-Z]/g).join('') +' = '+ word.match(/[a-zA-Z]/g).reverse().join(''));
    return word.match(/[a-zA-Z]/g).join('') === word.match(/[a-zA-Z]/g).join('');
};

'Anaaaa'.palindrome();

String.prototype.palindrome = function() {
  var r = this.split("").reverse().join("");
  return (r === this.valueOf());
}

var phrases = ["eve",
               "kayak",
               "mom",
               "wow",
               "noon",
               "Not a palindrome"];

for (var i = 0; i < phrases.length; i++) {
 var phrase = phrases[i];
 if (phrase.palindrome()) {
  console.log("'" + phrase + "' is a palindrome");
 } else {/*from w ww .  jav  a 2s . com*/
  console.log("'" + phrase + "' is NOT a palindrome");
 }
}

String.prototype.palindrome = function() {
  var palindrome = ["forwards", "backwards"];
  for (var i = 0; i < palindrome.length; i++) {
    var index = this.indexOf(palindrome[i]);
    if(index >= 0) {
      return true;
    }/*  w w  w .j a  v  a 2s  .com*/
  }
  return false;
};

var sentences = ["I'll send my car around to pick you up.",
                  "Let's touch base in the morning forwards",
                  "We dont backwards."];

for (var i = 0; i < sentences.length; i++) {
  var phrase = sentences[i];
  if (phrase.palindrome()){
    console.log("PALINDROME ALERT " + phrase);
  }
}

String.prototype.palindrome = function(){

// Advanced Solution
// we need to use valueOf() because 'this' is a function
//   var inputArray = this.split('').reverse().join('');
//   return (inputArray === this.valueOf());
// };/*from  w  ww. j  a va  2 s . com*/

var len = this.length-1;

for (var i = 0; i < len; i++) {
  if (this.charAt[i] !== this.charAt[len-i]) {
    return false;
  }
  if (i === (len-i)) {
    return true;
  }
}
return true;

};

var phrases = ["eve", "kayak", "mom", "wow", "not a palindrome"];


for (var i = 0; i < phrases.length; i++) {
  var phrase = phrases[i];
  if (phrase.palindrome()) {
    console.log("'" + phrase + "' is a palindrome.");
  } else {
    console.log("'" + phrase + "' is NOT a palindrome.");
  }
}

String.prototype.palindrome = function() {
 var len = this.length-1;
 for (var i = 0; i <= len; i++) {
  if (this.charAt(i) !== this.charAt(len-i)) {
   return false;/*from   w w  w .jav  a2 s .  c om*/
  }
  if (i === (len-i)) {
   return true;
  }
 }
 return true;
};