Nodejs String Palindrome Check palindrome()

Method Source Code

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  .j  a va2 s  . c o m
      if (i === (len-i)) {
         return true;
      }
   }
   return true;
};

// 
// SUPER advanced way
//
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");
   }
}

Related

1. 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;
     return false;
   ...
   

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('');
   

5. palindrome(str)

   function palindrome(str) {
     str = str.replace(/[^a-zA-Z0-9]+/gi, '').toLowerCase();
       return str == str.split('').reverse().join('');
   palindrome("eye");