Nodejs String Palindrome Check palindrome()

Method Source Code

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  .  ja  v  a  2  s  .co m
  }
  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);
  }
}

Related

1. 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;
       if (i === (len-i)) {
         return true;
     return true;
   };
   String.prototype.palindromeAdv = 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 {
       console.log("'" + phrase + "' is NOT a palindrome");
   

2. palindrome()

   String.prototype.palindrome = function() {
       for (var i = 0; i <= this.length - 1; i++) {
           if (this.charAt(i) !== this.charAt(len - i)) {
               return false;
           if (i === (len - i)) {
               return true;
       return true;
   };
   String.prototype.palindromeAdv = function() {
       var r = this.split("").reverse().join("");
       return (r === this.valueOf());
   };
   

3. palindrome()

   'use strict';
   String.prototype.palindrome = String.prototype.palindrome || function ( ) {
     if ( typeof this == 'string' ) {
       return this === this.split('').reverse().join('');
     else {
       return false;
   };
   ...
   

4. palindrome(loose)

   String.prototype.palindrome = function(loose) {
       var str = loose ? this.replace(/[^a-zA-Z0-9]+/gi, '').toLowerCase() : this;
       return str == str.split('').reverse().join('');