# Palindrome number in JavaScript

a number is a palindrome if the reversed number is equal to the original number. for example, 121, 101, and 12321 are palindrome numbers.

## Palindrome in JavaScript using while loop

In this program, you will take input from users using a window prompt, and you will check whether the number is a palindrome or not using a while loop.

``````<!DOCTYPE html>
<html>
<body>
<script>
function Palindrome() {
var r,rev=0,n,copy;
n = parseInt(prompt("enter a number:"));
copy=n;
while (n != 0) {
r = n % 10;
rev = rev * 10 + r;
n = parseInt(n / 10);
}
if(copy==rev)
{
document.write(copy+" is palindrome a number");
}
else
{
document.write(copy+" is not palindrome a number");
}
}
</script>
<form>
<input type="button" value="Palindrome" onclick="Palindrome();" />
</form>
</body>
</html>
``````

Input has been taken through the javascript prompt method

## output

```enter a number:12321
12321 is palindrome a number
```

### explanation of palindrome program to check whether a number is palindrome or not:

• when the user clicks on the palindrome button, Palindrome function will get called.
• inside palindrome function asked the user to enter a positive number which is stored in the variable `n`.
• The number is saved into another variable `copy` to check it when we need to compare our original number with the reverse number.
• Inside the loop, one by one last digit number is separated using code `n%10` and `rev*10` will maintain their nth position.
• After reversing the digits, compare a reverse value with the original value which is stored in the copy variable. you will compare an original value with the copy value by using the if statement i.e `if(copy==rev) { }`.
• If the numbers are equal, then the number is a palindrome, otherwise, it's not.

## Program to check Palindrome number in JavaScript using for loop

In this program, you will take input by using a window prompt method, and you will check whether the number is a palindrome or not using a for loop.

``````<!DOCTYPE html>
<html>
<body>
<script>
function Palindrome() {
var r,rev=0,n,copy;
n = parseInt(prompt("enter a number:"));
copy=n;
for(;n != 0; n = parseInt(n / 10);)
{
//find reminder
r = n % 10;
// reverse the number
rev = rev * 10 + r;
}
// compare reverse number with original number
if(copy==rev)
{
document.write(copy+" is palindrome a number");
}
else
{
document.write(copy+" is not palindrome a number");
}
}
</script>
<form>
<input type="button" value="Palindrome" onclick="Palindrome();" />
</form>
</body>
</html>

``````

Input has been taken through the javascript prompt method

## output

```enter a number:23432
23432 is palindrome a number
```

## Program to check Palindrome number in JavaScript using do while loop

In this program, you will check whether the number is a palindrome or not by using a do while loop.

``````<!DOCTYPE html>
<html>
<body>
<script>
// check palindrome number by using do while loop
function Palindrome() {
var r,rev=0,n,copy;
// take input from user stored in n
n = parseInt(prompt("enter a number:"));
copy=n;
do{
// get reminder
r = n % 10;
// reverse the number
rev = rev * 10 + r;
n = parseInt(n / 10);
} while (n != 0);
if(copy==rev)
{
document.write(copy+" is palindrome a number");
}
else
{
document.write(copy+" is not palindrome a number");
}
}
</script>
<form>
<input type="button" value="Palindrome" title="check palindrome number" onclick="Palindrome();" />
</form>
</body>
</html>
``````

Input has been taken through the javascript prompt method

## output

```enter a number:53435
53435 is palindrome a number
```