Step 1: Understand the Math Behind the Surface Area of a Sphere

Before we dive into writing the function, we first need to understand the math. The formula to calculate the surface area of a sphere is 4πr^2. Where r is the radius of the sphere and π is a mathematical constant whose approximately value is 3.14159.

const pi = Math.PI; // approx 3.14159

Step 2: Define the Function and Accept the Radius as Argument

Next, we'll define a function named calculateSurfaceAreaSphere. This function will accept one argument, the radius of the sphere.

function calculateSurfaceAreaSphere(radius) {
  // calculation will be done here
}

Step 3: Validate the Input

We need to make sure the radius provided is a positive number. If it's not, we'll throw an error.

function calculateSurfaceAreaSphere(radius) {
   if (typeof radius !== 'number' || radius <= 0) {
     throw new Error('Radius must be a positive number');
   }
}

Step 4: Calculate the Surface Area

Now, we can calculate the surface area of the sphere using the formula discussed in the first step and return the result.

function calculateSurfaceAreaSphere(radius) {
  if (typeof radius !== 'number' || radius <= 0) {
    throw new Error('Radius must be a positive number');
  }

  const surfaceArea = 4 * pi * Math.pow(radius, 2);
  return surfaceArea;
}

Step 5: Test the Function

It's always a good idea to test our function to make sure it works as expected.

console.log(calculateSurfaceAreaSphere(5)); // should print: 314.1592653589793

In conclusion, this function takes in the radius as a parameter and calculates the surface area of a sphere. It first validates the input then applies the necessary mathematical formula to calculate and return the surface area.