<!DOCTYPE html>
<html>
<body>
<p>Click the button to display the avail height of your screen, in pixels.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var x = "Avail Height: " + screen.availHeight + "px";
window.alert(x);
}
</script>
</body>
</html>