JavaScript Functions: Storing Functions As Values

JavaScript is a flexible language, and that flexibility extends to functions.  A JavaScript function are not just codes that you reuse and execute.  There are also values, values that you assign to a variable.  In the following example we are going to write a function that will calculate the radius of a circle.  But instead of invoking radius function like a normal function call, we are going to assign to a function to a variable first.

    <script>

        var r = radius;

        function radius(circumference) {
            return circumference / (2 * Math.PI);
        }

        console.log(r(10));

    </script>

The code above returns a value of the radius by dividing the circumference by 2*Math.PI and outputting the result to the console log.  Notice once we assign the function to the radius to variable r, we can use the variable r in place of the function radius.

Here is the result: