JavaScript iterative solution with 72 ms, faster than 100%
using inorder traverse\njs\n/**\n * @param {TreeNode} root\n * @param {number} k\n * @return {number}\n */\nvar kthSmallest = function(root, k) {\n    let resul
using inorder traverse\n``` js\n/**\n * @param {TreeNode} root\n * @param {number} k\n * @return {number}\n */\nvar kthSmallest = function(root, k) {\n    let result = null;\n    function _kthSmallest(node) {\n        if (!node) return;\n        _kthSmallest(node.left);\n        k--;\n        if (k === 0) {\n            result = node.val;\n            return;\n        }\n        _kthSmallest(node.right);\n    }\n    _kthSmallest(root);\n    return result;\n};\n```
['JavaScript']