JavaScript program to calculate circle area

Following program shows you how to calculate circle area.
In this tutorial will get circle radius from user and calculate area and prints it using following formula
Area = PI X r X r

var circleRadius = parseInt(prompt("Please enter the radius of circle:"));
var areaOfCircle = Math.PI * (circleRadius * circleRadius);
console.log("Area of circle is: " + areaOfCircle);

Output:

Please enter the radius of circle:
4
Area of circle is: 50.26548245743669