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