Write a JavaScript program to find largest among two numbers.
<html>
<head>
<title>Largest of two numbers</title>
</head>
<body>
<script type="text/javascript">
var a, b;
a = 15;
b = 75;
if(a > b)
document.write("<h2>a is largest number</h2>");
else
document.write("<h2>b is largest number</h2>");
</script>
</body>
</html>
