<!DOCTYPE html>
<html>
<head></head>
<body>
<script>
var arr = [1, 2, 3, 4, 5, 6];
var sum = 0
for (var i = 0; i < arr.length; i++)
sum += arr[i];
document.writeln("average = " + sum / arr.length + "<br />"); </script>
</body>
</html>
<!--
run:
average = 3.5
-->