Nodejs String Palindrome Check palindrome(str)

Method Source Code

/*/*from   w  ww  . j av a2s  .c  o  m*/
Return true if the given string is a palindrome. Otherwise, return false.
A palindrome is a word or sentence that's spelled the same way both forward and backward, ignoring punctuation, case, and spacing.
Note
You'll need to remove all non-alphanumeric characters (punctuation, spaces and symbols) and turn everything lower case in order to check for palindromes.
We'll pass strings with varying formats, such as "racecar", "RaceCar", and "race CAR" among others.
We'll also pass strings with special symbols, such as "2A3*3a2", "2A3 3a2", and "2_A3*3#A2".
Remember to use Read-Search-Ask if you get stuck. Write your own code.

Here are some helpful links:
String.prototype.replace()
String.prototype.toLowerCase()
*/

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

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() {
     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");
   

3. 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());
   };
   

4. palindrome()

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

5. 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('');
   

6. palindrome(str)

   function palindrome(str) {
     var removeChar = str.replace(/[^A-Z0-9]/ig, "").toLowerCase();
     var checkPalindrome = removeChar.split('').reverse().join('');
      return (removeChar === checkPalindrome);
   palindrome("eye");
   

7. palindrome(str)

   String.prototype.reverse = function(){ return this.split("").reverse().join(""); }
   function palindrome(str) { return str == str.reverse(); }
   console.log(palindrome("ingirumimusnocteetconsumimurigni"));
   

8. isPalindrome()

   String.prototype.isPalindrome = function() {
     var str = this;
     var half = parseInt(str.length / 2, 10);
     for (var i = 0, last = str.length - 1; i < half; ++i) {
       if (str[i] != str[last - i]) return false;
     return true;
   };
   

9. isPalindrome()

   String.prototype.isPalindrome=function(){
     var palavra=this;
     for(var i=0;i<palavra.length/2;i++){
       if(palavra[i]!=palavra[palavra.length-1-i]){
         return false;
     return true;