Palindrome Checker Using JavaScript

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Introduction of the Project

A palindrome is a word, phrase, number, or other sequences of characters which reads the same backward or forward. In this JavaScript tutorial, we will be discussing the concept of palindrome numbers and learning how to build a Palindrome checker using JavaScript. This javascript application will help us to check if a given number is a palindrome or not and help us understand the basics of looping, string manipulation, and conditional statements in JavaScript.

By the end of this tutorial, you will have a deeper understanding of how to write simple algorithms in JavaScript to solve real-world problems.


1. To understand what a palindrome number is and how it works.

2. To understand the basics of looping and conditional statements in JavaScript.

3. To extract the data entered by the user and check if it is a palindrome or not.

4. To test the program with various examples and verify its accuracy.

5. To learn how to debug and troubleshoot errors in the program.

6. To gain practical experience in writing simple algorithms in JavaScript.

7. To understand the importance of commenting code and documenting the steps taken.


1. Knowledge of HTML to structure the site and CSS to design and layout the webpage.

2. A Basic understanding of JavaScript syntax and programming concepts.

3. A text editor or integrated development environment (IDE) to write and run JavaScript code. (We have used Visual Studio Code)

4.  Web browser to run and test the JavaScript program.

5. Understanding of number manipulation and string manipulation in JavaScript.

6. Familiarity with conditional statements and loops in JavaScript.

7. Knowledge of the built-in JavaScript functions for string manipulation.

Source Code


<!DOCTYPE html>
<html lang="en">
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Palindrome Checker</title>
<link rel="stylesheet" href="style.css">
<label for="fname">Enter a palindrome to check:</label>
<input type="text" id="number" name="number"><br><br>
<button onclick="check()">CHECK</button>
<script src="palindrome.js"></script>

CSS Code

margin-top: 300px;
margin-left: 500px;


function check(){
let data = document.getElementById('number').value;
let a = '';
for(let i=data.length-1;i>=0;i--){
alert(data+' IS A PLAINDROME');
}else alert(data+' IS NOT A PALINDROME');

Explanation of the Code

1. Firstly, we used HTML to create the basic layout of the webpage.

2. Then, we created a text field and a button to check the result.

3. Once we had the basic layout ready, we applied CSS to add the padding by using margins.

Moving to the palindrome checking process:

1. First, we take the input from the user and store the actual value in a variable and reverse the string and store it in another variable.

2. Finally, apply a check for the variables. If they are equal, then display the alert box with the message “It is a palindrome” else, display “It is not a palindrome”.


Main Interface

Palindrome Checker Using JavaScript

Points To Remember

We have successfully built a palindrome checker using JavaScript that checks the number or string for the palindrome. It extracts data entered by the user, apply the check mechanism, and displays the alert box accordingly. It is a very easy way to check for any number to be a palindrome. Try this Javascript project on your now. Here are a few points that you need to keep in mind while working on this project idea.

  • In JavaScript, numbers need to be converted to strings in order to be manipulated.
  • Loops and conditional statements are fundamental concepts in writing algorithms in JavaScript.
  • The program should check the reverse of the given number and compare it to the original number.
  • If the reverse of the number is equal to the original number, it is a palindrome.
  • The program should handle edge cases and return appropriate messages for numbers with leading zeros or negative numbers.
  • Proper commenting and documentation of code are important for maintainability and understanding of the program.
  • Continuously test the program with various examples to verify its accuracy.


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