js_task1.html

<!DOCTYPE html>
<html lang="en">
<head>
    <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>JS task 1</title>
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha3/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-KK94CHFLLe+nY2dmCWGMq91rCGa5gtU4mk92HdvYe+M/SXH301p5ILy+dN9+nJOZ" crossorigin="anonymous">
    <script>
        function reverse(x){
            document.getElementById('restr').innerHTML=x.toString().split("").reverse().join("");
        }
    </script>
</head>
<body>
    <div class="container">
        <h1 class="text-center mt-5">Reverse number x:</h1>
        <input type="text" id="str" class="form-control mt-5">
        <button id="reverse" class="btn btn-dark my-4 d-block mx-auto" onclick="reverse(document.getElementById('str').value)">Reverse</button>
        <p id="restr"></p>
    </div>
</body>
</html>