merge-sort

let articleContent = document.querySelector(".article-content")
// Create sorting elements
let size = 10
for (let i = 0; i < size; i = i + 1){
    let sortItem = document.createElement("div")
    sortItem.classList.add("sortItem")
    sortItem.style = "display: inline-block; border: solid black 2px; padding: 1rem"
    sortItem.innerHTML = Math.floor(Math.random() * 20)
    articleContent.prepend(sortItem)
    // add the element at the top of the div
}
let sortItems = Array.from(document.querySelectorAll(".sortItem"))

function combine(array1, array2){
    let pivot = 0
    let sortedArray = []
    // check whether pivot index is in the array
    // when the pivot index increased larger than
    while( (pivot in left) || (pivot in right) )
        if (pivot in left && pivot in right){
            if (left[pivot] <= right[pivot]){
                sortedArray.push(left[pivot])
                sortedArray.push(right[pivot])
            }
            else{
                sortedArray.push(right[pivot])
                sortedArray.push(left[pivot])
            }
        }
        else if (pivot in left){
            sortedArray.push(left[pivot])
        }
        else if (pivot in right){
            sortedArray.push(right[pivot])
        }
    pivot += 1
    return sortedArray
}
function mergesort(array){
    console.log(array)
    if (array.length == 1 || array.length == 0){
        return array
    }
    left = array.slice(0, Math.floor(sortItems.length / 2))
    right = array.slice(Math.floor(sortItems.length / 2))
    console.log("left")
    console.log(left)
    console.log("right")
    console.log(right)
    mergesort(left)
    mergesort(right)
    return combine(left, right)
}
mergesort(sortItems)