findArrayDifference()

Step 1: Understanding the Problem

Before we start writing our function, we first need to clarify what the problem is asking for. We are asked to find the difference between two arrays. This means we need to create a function that takes in two arrays, finds the unique elements that are only present in one array but not the other, and returns a new array containing these unique elements.

Step 2: Setting Up Our Function

In JavaScript, we begin writing a function using the function keyword, followed by the name of the function, and then the parameters it accepts in parentheses. We are calling our function findArrayDifference, and it will take in two parameters, array1 and array2.

function findArrayDifference(array1, array2) {
  
}

Step 3: Finding the Difference

The easiest way to find the difference between two arrays in JavaScript is to use the filter and includes methods.

.filter is a method available on all arrays and it will return a new array with only the elements that pass a certain condition. In our function, we want to return all the elements from array1 that are not included in array2. To check this, we can use the .includes method, which checks whether an array contains a certain item.

function findArrayDifference(array1, array2) {
  let difference = array1.filter(x => !array2.includes(x));
}

Step 4: Returning the Difference

After we've found the difference, the only remaining step is returning it. In JavaScript, we achieve this with the return statement:

function findArrayDifference(array1, array2) {
  let difference = array1.filter(x => !array2.includes(x));
  return difference;
}

Step 5: Combining Differences

At this point, our function only finds the unique elements in array1 that are not in array2. However, we also need to find the unique elements in array2 that are not in array1. We use the same method as step 3,; then we need to join both arrays, and for this, we will use the concat method:

function findArrayDifference(array1, array2) {
  let difference1 = array1.filter(x => !array2.includes(x));
  let difference2 = array2.filter(x => !array1.includes(x));
  return difference1.concat(difference2);
}

Conclusion

There you have it! Our findArrayDifference function is complete. It takes in two arrays as arguments, finds the elements that are unique to each array, and returns a new array containing these elements. This is a practical example of using functional programming methods in JavaScript, showcasing the power and simplicity of the filter, includes, and concat methods.