Nodejs String Palindrome Check isPalindrome()

Method Source Code

'use strict';/*  w w w .  ja va2  s  . c  o m*/

/**
 * Check if a string is the same written forward and backwards.
 * This implementation is faster than doing standard convert to array, reverse, join pattern.
 * @returns {Boolean} True if value is same forward and backwards
 */
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;
};

Related

1. 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");
   

2. palindrome(str)

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

3. 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;
   };
   

4. 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;
   

5. 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();  
   ...
   

6. 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--) {
   ...
   

7. isPalindrome()

   var first = 999,
       second = 999,
       largestPalindromicProduct = 0;
   String.prototype.isPalindrome = function() {
     return this == this.reverse();
   while(first > 99) {
     second = first;
     while(second > 99) {
   ...
   

8. 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--;
   ...
   

9. 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('');