Binary Tree Level Order Traversal II | LeetCode 107

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Great resource I use to learn algorithms.
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Here is the full implementation.

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number[][]}
 */
let levelOrderBottom = function(root) {
    let result = [];
    
    if (root === null) {
        return result;
    }
    
    let queue = [];
    queue.push(root);
    
    while (queue.length !== 0) {
        let nodeCount = queue.length;
        let rowResult = [];
        
        while (nodeCount > 0) {
            let currentNode = queue.shift();
            
            if (currentNode.left !== null) {
                queue.push(currentNode.left);
            }
            
            if (currentNode.right !== null) {
                queue.push(currentNode.right);
            }
            
            rowResult.push(currentNode.val);
            nodeCount--;
        }
        
        result.unshift(rowResult);
    }
    
    return result;
};