Palindrome in Javascript


In this javascript algorithm exercise, I would be sharing how to write a palindrome algorithm in javascript.

What is a Palindrome ?

Palindromes are strings that form the same word if it is reversed. Palindromes were first discovered in ancient Greek Scrolls

How to solve isPalindrome in Javascript

Given a string, return true if the string is a palindrome or false if it is not. Do include spaces and punctuation in determining if the string is a palindrome.


  • palindrome("abba") === true
  • palindrome("abcdefg") === false

Let’s solve this

function isPalindrome(str) {
  return str.split('').reverse().join('') === str ? true : false

This method uses Javascripts inbuilt string and array methods, to split a string into an array like we did in our reverse string algorithm earlier, reverse it and then join it back, this then returns TRUE or FALSE if the output is the same as input when returned.

Let’s take a look at our function closely


  // our function below
  function isPalindrome(str) {
    let stringToArray = str.split("") // output here is an array ['a','d','b']
    let stringToArrayReversed = stringToArray.reverse("") // the output here is a reversed array of  ['b','d','a']
    let reversedString = stringToArrayReversed.join(""); // The array join method would join the array into a string "bda"
    return (reversedString === str) ? true : false

Without the True or False Statement our expression will return an implicit True or False when using the === operator if str and our reversedString are the same. In this case ‘adb’ and ‘bda’ are not the same and would return false.

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