findPrimeFactors()

Step 1: Understand the problem and Create the Basic Structure

Before we start writing the function, we need to understand what prime factors are. Prime factors are a factor that is a prime number. In other words, a number which has only two positive divisors, 1 and the number. For example, the prime factors of 15 are 3 and 5. These are the only two numbers that divide 15 and are also prime numbers.

With that clear, let's begin with creating a function called findPrimeFactors. This function will take an integer num as an argument. Here is how our basic structure will look like:

function findPrimeFactors(num) {
    // our code will go here
}

Step 2: Initialize an empty array

We need a data structure to hold the prime factors that we find. An array is an ideal choice because it can hold multiple values. Create an array primeFactors and initialize it as an empty array.

function findPrimeFactors(num) {
    let primeFactors = [];
    // our code goes here
}

Step 3: Write loop to find prime factors

We will write a loop that starts from 2 (as it's the first prime number) and runs until our input number. Inside the loop, we will write another while loop to check if the number is divisible. If it is, then it's a prime factor and we will push this factor to our primeFactors array. The code looks like this:

function findPrimeFactors(num) {
    let primeFactors = [];
    for(let i = 2; i <= num; i++) {
        while(num % i === 0) {
            primeFactors.push(i);
            num /= i;
        }
    }
    // our code goes here
}

Step 4: Return the result of the function

Once we have pushed all prime factors into our array, there is one last thing that needs to be done. We need to return this array to the caller. This can be achieved by adding a return statement at the end of our function.

function findPrimeFactors(num) {
    let primeFactors = [];
    for(let i = 2; i <= num; i++) {
        while(num % i === 0) {
            primeFactors.push(i);
            num /= i;
        }
    }
    return primeFactors;
}

Conclusion

In conclusion, we've managed to create a function that finds and returns the prime factors of a given number. Remember before diving into code, you should understand the problem properly. After creating the basic structure, initialize necessary variables or arrays. Then write actual logic of finding prime factors and then finally in the end, return the result. These steps make it easier to handle a problem and code it in a clean, manageable way.

Here is the final implementation of our function:

function findPrimeFactors(num) {
    let primeFactors = [];
    for(let i = 2; i <= num; i++) {
        while(num % i === 0) {
            primeFactors.push(i);
            num /= i;
        }
    }
    return primeFactors;
}