calculateAreaParallelogram()

Step 1: Understand the Problem

Before we can even begin to write our function, it's necessary to understand the problem we're trying to solve. We want a function that will calculate the area of a parallelogram.

The formula for the area of a parallelogram is base * height. We will receive two parameters which represent the base and height of a parallelogram, and return the area of the parallelogram as a result of the function.

Step 2: Create a Function Shell

Now that we understand the problem, let's create a function shell. It means creating a function without its actual implementation. In this case, we will create a function called calculateAreaParallelogram and it would take two parameters: base and height.

For the time being, our function doesn't return anything.

function calculateAreaParallelogram(base, height) {

}

Step 3: Implement the Function

Now, we're ready to implement the function. Our job is to calculate the area of the parallelogram. To achieve this, we should multiply the base by the height.

Let's add that inside our function.

function calculateAreaParallelogram(base, height) {
    return base * height;
}

Step 4: Testing

At this point, our function should work. Let's test our function to ensure it's working as expected. To do this, we will call the function with a pair of test values for base and height, and print out the result.

console.log(calculateAreaParallelogram(10, 5));  // should print 50

Step 5: Refactor and Conclusion

Now that we have tested our function and it works perfectly, the code is ready for use. This function should suffice for calculating the area of a parallelogram given any base and height.

Here's the final code:

function calculateAreaParallelogram(base, height) {
    return base * height;
}

console.log(calculateAreaParallelogram(10, 5));  // should print 50

In conclusion, we started by understanding the problem, then wrote an initial shell for our function. After that, we implemented the logic for calculating the area of a parallelogram and tested our function. Finally, we refactored the code to ensure it is clean, readable, and modular. Now, you can use this function to calculate the area of any parallelogram!