<!DOCTYPE html>
<html>
<body>
Checkbox: <input type="checkbox" id="myCheck" value="myvalue">
<p>Click the "Try it" button to display the value of the value attribute of the checkbox.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var x = document.getElementById("myCheck").value;
document.getElementById("demo").innerHTML = x;
}
</script>
</body>
</html>