I'll start off by saying I'm not very proud of this one. It didn't take long but I definitely over thought it. Should've been A => B but I took a wandering path instead.

• - Details

Given two integers a and b, which can be positive or negative, find the sum of all the integers between including them too and return it. If the two numbers are equal return a or b.

Note: a and b are not ordered!

• - First, I defined the length of the array I wanted to build

    const length = Math.abs(b - a)

The Math.abs came after I realized that I would need the absolute value of these numbers since there could be some negatives involved.

• - Then, I used a method I wasn't too familiar with and glad I came across it.

    const numberArr = Array.from({length: length+1}, (_, i) => i + c)

All this is doing is accepting the length of my array as an object (I had to add 1 since my previous logic wasn't correct) then taking in a map function to start at a constant I've defined as c.

• - Here's my logic on my c constant

    let c = null
    a < b ? c = a : c = b

I'm first declaring c as a variable then running a ternary operator to define c as my array starting point depending on which value is smaller between a and b.

• - Time to sum them up

    const total = numberArr.reduce((total, item) => {
        return total += item}, 0)

I used the array method .reduce() to sum up the array since I was familiar with this method and it happens to be one of my faves.

• SOLUTION

Here's the final code block:

    function getSum( a,b ) {
        let c = null
        const length = Math.abs(b - a)

        a < b ? c = a : c = b

        const numberArr = Array.from({length: length+1}, (_, i) => i + c)

        const total = numberArr.reduce((total, item) => {
            return total += item}, 0)

        return total
    }