The atan() method of math object returns the arctangent of a number. Use it for example to get arctangent of a number.
Syntax
Math.atan(num)
<html>
<head>
<script type="text/javascript">
var num = .6
document.write(Math.atan(num) + "</br>");
document.write(Math.atan(1) + "</br>");
document.write(Math.atan(2) + "</br>");
</script>
</head>
<body>
</body>
</html>