<!DOCTYPE html>
<html>
<body>
Month: <input type="month" id="myMonth">
<p>Click the button to change the value of the step attribute of the month field.</p>
<p><b>Tip:</b> Open the calendar on the right side of the month field before and after you click the button, to see the effect.</p>
<button onclick="myFunction()">Try it</button>
<p><strong>Note:</strong> input elements with type="month" are not supported in Internet Explorer or Firefox.</p>
<p id="demo"></p>
<script>
function myFunction() {
document.getElementById("myMonth").step = "2";
document.getElementById("demo").innerHTML = "Step was set to '2', meaning that the user can only select every second month in the calendar.";
}
</script>
</body>
</html>