check-month

<!DOCTYPE html>
<html>
<body>

<input type="number" id="myNumber" value="">

<p>Enter the month.</p>

<button onclick="myFunction()">Check if entered month is valid</button>

<script>
    function myFunction() {

        // get the input typed by user
        var month = document.getElementById("myNumber");

        // convert the value to a number
        var monthAsNumber = Number(month.value);

        // check that the value is between 1 and 12
        if(monthAsNumber >= 1 && monthAsNumber <= 12) {
            alert('The month introduced is valid');
        } else {
            alert('Your value is out of range');
        }
    }
</script>

</body>
</html>