Heapify javascript

heap.js

class Heap {
    buildHeaps(nums) {
        for (let i = Math.ceil(nums.length / 2) - 1; i >= 0; i--) {
            this.heapify(nums, i)
        }
    }

    heapify(nums, i) {
        let l = i * 2 + 1
        let r = l + 1

        let max = i
        if (r <= nums.length) {
            max = nums[l] > nums[r] ? l : r
        } else if (l <= nums.length && nums[l] > nums[i]) {
            max = l
        }
        if (max !== i) {
            this.swap(nums, max, i)
            this.heapify(nums, max)
        }
    }

    swap(nums, max, i) {
        if (nums[max] > nums[i]) {
            let temp = nums[i]
            nums[i] = nums[max]
            nums[max] = temp
        }
    }
}

let h = new Heap()
let nums = [2, 5, 3, 60, 11, 20, 1, 45, 7]
h.buildHeaps(nums)

console.log(nums)