To get the arctangent of a number, use the atan() method in JavaScript. This method returns the arctangent in radians of a number. The atan method returns a numeric value between -pi/2 and pi/2 radians.
Example
You can try to run the following code to get the arctangent of a number in JavaScript −
<html>
<head>
<title>JavaScript Math atan() Method</title>
</head>
<body>
<script>
var value = Math.atan(-1);
document.write("First Value : " + value );
value = Math.atan(.5);
document.write("<br />Second Value : " + value );
value = Math.atan(30);
document.write("<br />Third Value : " + value );
var value = Math.atan("Demo Text");
document.write("<br />Fourth Value : " + value );
</script>
</body>
</html>