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JavaScript Reverse Number

In this program, you will take input from a user and find the reverse of a number.
For example reverse of the number 1354 is 4531.

Reverse function in JavaScript

<!DOCTYPE html>
<html>
  <body>
    <script>
      function reverse() {
        var r,rev=0,n;
        n = parseInt(prompt("enter a number:"));
        while (n != 0) {
          r = n % 10;
          rev = rev * 10 + r;
          n = parseInt(n / 10);
        }
        document.write("reverse of number is:"+rev);
      }
    </script>
    <form>
      <input type="button" value="reverse" onclick="reverse();" />
    </form>
  </body>
</html>

Run now

Input has taken through javascript prompt method

output

enter a number:1245
reverse of number is:5421

working of Reverse number

In the above program, asked the user to enter a positive number which is store in the variable n
Inside the loop, one by one last digit number is separated using code n%10 and rev*10 will maintain their n^th position
Remove one by one last digit parseInt(n / 10)

Reverse number program in JavaScript using do while loop

In this program, you will take numbers from users using the javascript prompt method and reverse those numbers by using do-while loop

<!DOCTYPE html>
<html>
  <body>
    <script>
     function reverse() {
       var r,rev=0,n;
        n = parseInt(prompt("enter a number:"));
        do{
          r = n % 10;
          rev = rev * 10 + r;
          n = parseInt(n / 10);
        }while(n != 0);
        document.write("reverse of number is:"+rev);
      }
    </script>
    <form>
      <input type="button" value="reverse" onclick="reverse();" />
    </form>
  </body>
</html>

Input has taken through javascript prompt method

output

enter a number:1245
reverse of number is:5421

Reverse number program in JavaScript using for loop

In this program, you will take numbers from users using the javascript prompt method and reverse those numbers by using for loop

<!DOCTYPE html>
<html>
  <body>
    <script>
      function reverse() {
       var r,rev=0,n;
        n = parseInt(prompt("enter a number:"));
	for(;n != 0; n = parseInt(n / 10))
        {
          r = n % 10;
          rev = rev * 10 + r;
        }
        document.write("reverse of number is:"+rev);
      }
    </script>
    <form>
      <input type="button" value="reverse" onclick="reverse();" />
    </form>
  </body>
</html>

output

enter a number:34567
reverse of number is:76543

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