To get the cosine of a number in JavaScript, use the Math.cos() method. The cos method returns a numeric value between -1 and 1, which represents the cosine of the angle.
Example
You can try to run the following code to get the cosine of a number −
<html> <head> <title>JavaScript Math cos() Method</title> </head> <body> <script> var value = Math.cos(90); document.write("First Value : " + value ); value = Math.cos(30); document.write("<br />Second Value : " + value ); value = Math.cos(-1); document.write("<br />Third Value : " + value ); value = Math.cos(2*Math.PI); document.write("<br />Fourth Value : " + value ); </script> </body> </html>