Nodejs String Palindrome Check isPalindrome()

Method Source Code

// 004 Find the largest palindromic product of two three-digit numbers

var first = 999,//from   w w  w  .  j  a va2 s  .c o  m
    second = 999,
    largestPalindromicProduct = 0;


String.prototype.isPalindrome = function() {
   return this == this.reverse();
}

while(first > 99) {
   second = first;
   while(second > 99) {
      var product = first * second;
      if(product.toString(10).isPalindrome() && product > largestPalindromicProduct)
         largestPalindromicProduct = product;
      second--;
   }
   first--;
}

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

Related

1. 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;
   };
   

2. 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;
   

3. isPalindrome()

   String.prototype.isPalindrome = function() {
     var val = this.toString().toLowerCase();
     var reverse = val.split('').reverse().join('');
     return val === reverse;
   var str = 'something';
   var result = str.isPalindrome();  
   var str2 = 'level';
   var result2 = str2.isPalindrome();  
   ...
   

4. isPalindrome()

   'use strict';
   String.prototype.isPalindrome = String.prototype.isPalindrome || function () {
     let length = Math.floor(this.length / 2);
     for (let i = 0; i < length; i++) {
       if (this[i] !== this[this.length - i - 1]) {
         return false;
     return true;
   ...
   

5. isPalindrome()

   String.prototype.isPalindrome = function () {
     return this.valueOf() === this.reverse().valueOf();
   };
   String.prototype.reverse = function () {
     return Array.prototype.slice.apply(this).reverse().join('');
   };
   let result = 0;
   for (let i = 999; i > 0; i--) {
     for (let j = i; j > 0; j--) {
   ...
   

6. isPalindrome()

   var isPalindrome = function(str){
     var i = 0;
     var j = str.length-1;
     while (i <= j){
       if (str[i] != str[j]){
         return false;
       i++;
       j--;
   ...
   

7. isPalindrome()

   String.prototype.isPalindrome = ()=>{
     return this.replace(/[^a-zA-Z ]/g, "").replace(/ /g,'').trim().toLowerCase() == this.replace(/[^a-zA-Z ]/g, "").replace(/ /g,'').trim().toLowerCase().split('').reverse().join('');
   

8. isPalindrome()

   var isPalindrome = function(inString) {
     var inString = inString.toLowerCase();
     for (var i = 0, j = inString.length-1; i < inString.length/2; i++, j--) {
       if (inString[i] != inString[j]){
         return false;
     return true;
   String.prototype.isPalindrome = function isPalindrome() {
     console.log(this);
     var new_str = this.toString().replace(" ", "");
     if (new_str == new_str.split("").reverse().join("")) {
       return true;
     } else {
       return false;