Recursive merge sort, written in CoffeeScript

mergeSort.coffee

nums = [8,7,9,6,5,4,3,2,1,0]

mergeSort = (list)->
        if list.length <= 1 then return list
        left = []
        right = []
        for x in list
                if left.length < Math.floor(list.length / 2) then left.push(x)
                else right.push(x)
        left = mergeSort(left)
        right = mergeSort(right)
        return merge(left, right)

merge = (left, right)->
        result = []
        ll = left.length
        rl = right.length
        while ll > 0 || rl > 0
                if ll > 0 and rl > 0
                        if left[left.length - ll] > right[right.length - rl]
                                result.push left[left.length - ll]
                                ll -= 1
                        else
                                result.push right[right.length - rl]
                                rl -= 1
                else if ll > 0
                        result.push left[left.length - ll]
                        ll -= 1
                else if rl > 0
                        result.push right[right.length - rl]
                        rl -= 1
        return result

res = mergeSort(nums)
console.log res