Binary Tree Right Side View

Problem statement

Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

Example 1:

Input: root = [1,2,3,null,5,null,4]Output: [1,3,4]

Example 2:

Input: root = [1,null,3]Output: [1,3]

Example 3:

Input: root = []Output: []

Constraints:

• The number of nodes in the tree is in the range [0, 100].
• -100 <= Node.val <= 100

My solution

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number[]}
 */
// var rightSideView = function(root, levels = 0, results = []) {
//     // console.log(levels, results)
//     if (!root) {
//         return results;
//     }
    
//     if (results[levels] === undefined) {
//         results[levels] = root.val;
//     }
    
//     levels++;
//     rightSideView(root.right, levels, results)
//     rightSideView(root.left, levels, results)
    
//     return results;
// };

var rightSideView = function(root) {
    if (!root) {
        return []
    }
    const queue = [root];
    const results = [];
    
    while (queue.length) {
        const size = queue.length;
        results.push(
            queue[size - 1].val
        )
        
        for (let i = 0; i < size; i++) {
            const current = queue.shift();
            
            if (current.left) {
                queue.push(current.left)
            }
            
            if (current.right) {
                queue.push(current.right)
            }
        }
    }
    
    return results;
}