calculateAreaSector()

Step 1: Begin by writing the initial function

In any JavaScript function, the first step is to write a function definition. In this case, the function is calculateAreaSector(). Check below on how you begin:

function calculateAreaSector() {

}

Step 2: Add parameters to the function

The function calculateAreaSector() is supposed to calculate the area of a sector of a circle. In order for it to do this, it needs to know the radius of the circle and the angle of the sector. These become parameters to the function.

function calculateAreaSector(radius, angle) {

}

Step 3: Implement the calculation

We know that the formula for the sector area of a circle is (angle/360) * π * radius^2. Hence, we program the function to perform this calculation. JavaScript has a built-in object for mathematical functions called Math which we can use.

function calculateAreaSector(radius, angle) {
    var area = (angle/360) * Math.PI * Math.pow(radius, 2);
}

Step 4: Returning the results

The final step within our function is to return the result of the calculation. This ends the function call and "sends back" the result to where the function was called.

function calculateAreaSector(radius, angle) {
    var area = (angle/360) * Math.PI * Math.pow(radius, 2);
    return area;
}

Conclusion:

That concludes the step-by-step guide to making a calculateAreaSector function. This is what it should look like:

function calculateAreaSector(radius, angle) {
    var area = (angle/360) * Math.PI * Math.pow(radius, 2);
    return area;
}

To test it, simply call the function with the radius and angle as parameters:

console.log(calculateAreaSector(5, 90));  // It should return 19.634954084936208