We can use math.pi to get the constant value of PI. The Math.PI property represents the ratio of the circumference of a circle to its diameter and the value of the PI is approximately 3.14159.
Because PI is a static property of Math, you always use it as Math.PI, rather than as a property of a Math object you created.
You can check the value of the Pi in JavaScript itself like as below example.
<html> <head> <title> Value of PI </title> </head> <body> <script language="JavaScript"> var result = Math.PI; document.write( "The Approximate value of PI is: " + result ); </script> </body> </html>
Output will be :
The Approximate value of PI is: 3.141592653589793
The following example is the simple implementation of the formula : A = PI * R* R, where R is the radius of the circle and A is the area of the circle.
<html> <head> <title>Find the area and circumference of a circle</title> </head> <body> <script language="JavaScript"> <!– function CalculateArea(){ var r =document.form1.txtRadius.value; document.write("<P>The area of the circle is " + (r * r * Math.PI) + "</p>"); } –> </script> <form name=form1> Enter the radius of circle: <input type="text" name="txtRadius" size=10> <br> <input type="button" value="Calculate" onClick='CalculateArea()'> </form> </script> </body> </html>
Thanks