Minimum Depth of Binary Tree | LeetCode 111

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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 minDepth = function(root) {
    if (root === null) {
        return 0;
    }
    
    let queue = [];
    queue.push(root);
    let depth = 0;
    
    while (queue.length !== 0) {
        let numberOfNodes = queue.length;
        
        while (numberOfNodes > 0) {
            let currentNode = queue.shift();
            
            if (currentNode.left === null && currentNode.right === null) {
                depth++;
                return depth;
            }
            
            if (currentNode.left !== null) {
                queue.push(currentNode.left);
            }
            
            if (currentNode.right !== null) {
                queue.push(currentNode.right);
            }
            
            numberOfNodes--;
        }
        
        depth++;
    }
};