<!DOCTYPE html>
<html>
<body>
<p>A function can access variables defined inside the function:</p>
<button type="button" onclick="myFunction()">Click Me!</button>
<p id="demo"></p>
<script>
function myFunction() {
var a = 4;
document.getElementById("demo").innerHTML = a * a;
}
</script>
</body>
</html>