Nodejs String Palindrome Check palindrome()

Method Source Code

'use strict';//from w w w. ja v a2 s . c  o m

// Define a repeatify function on the String object. 
// The function accepts an integer that specifies how many times the string has to be repeated.
// The function returns the string repeated the number of times specified. 
// For example: console.log('hello'.repeatify(3));
// Should print hellohellohello.


String.prototype.palindrome = String.prototype.palindrome || function ( ) {

   if ( typeof this == 'string' ) {

      return this === this.split('').reverse().join('');
      
   }
   else {

      return false;
   }

};
String.prototype.repeatify = String.prototype.repeatify || function ( times ) {

   var str = '';

   for ( var i = 0; i < times; i++ ) {
      
      str += this; 
   };

   return str;
};


// Make console.log('i am all lowercase'.capitalize()); to print 'I am all lowercase'

String.prototype.capitalize = String.prototype.capitalize || function ( ) {

   return this.charAt(0).toUpperCase() + this.slice(1);

};


console.log('i am all lowercase'.capitalize());

console.log('hello'.repeatify(3));

console.log('lol'.palindrome());
console.log('loll'.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() {
     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(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");
   

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"));