Day 086: Intermediate Algorithm Scripting (FCC)

I like the new FCC redesign! (recolor?)

I just finished the Functional Programming section on FCC. It took a few days to get through. I get why it is useful, but dang, it is a lot to take in. Callbacks seriously gets me cross eyed. And then when you add all the (new to me) methods like forEach(), map(), filter(), reduce() etc., it is a lot to take in!

At any rate, I am now heading into the Intermediate Algorithm Scripting section of FCC. I am trying to apply the Functional Programming principles to solving these challenges, so it is taking a bit longer to work through the problems.

What really helped me learn in the past was to collect a massive sheet of notes that I may or may not refer back to, but the act of putting it somewhere seems to help me understand it better some how? Or at the very least, it is good reference material. So here it is.

Intermediate Algorithm Scripting: Diff Two Arrays
I solved something similar in Edabit, but like I said, I wanted to get more practice in with the methods am not yet familiar with. I got that I needed to concat() the strings and knew filter() was the likeliest method that would help me find the answer, but I had some help from the Internets and StackOverflow to get the conditional statement correctly with the use of ! and includes() which I am not yet familiar with, nor would it be something I would have thought to use right away. I also poked around with trying to figure out how to refactor it a bit into all arrow functions, but rather move on to the next problem after a few failed attempts.

function diffArray(arr1, arr2) {
  var filterUnique = arr1.concat(arr2).filter((elem) => {
   if (!arr1.includes(elem) || !arr2.includes(elem)) {
     return elem;
    }
  })
  return filterUnique;
}