<!DOCTYPE html>
<html>
<body>
A hidden input field:
<input type="hidden" id="myInput" name="country" value="Norway">
<p>Click the buttons to display and/or change the value of the value attribute of the hidden input field.</p>
<button onclick="display()">Display value</button>
<button onclick="change()">Change value</button>
<script>
function display() {
var x = document.getElementById("myInput").value;
alert("The value of the hidden input field is: " + x);
}
function change() {
var x = document.getElementById("myInput").value="USA";
alert ("The value was changed to: " + x);
}
</script>
</body>
</html>