Create Binary Tree From Descriptions

/**
 * 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 {number[][]} descriptions
 * @return {TreeNode}
 */
var createBinaryTree = function(descriptions) {
    const map = new Map();
    const parentMap = new Map();

    for (const [parent, child, isLeft] of descriptions) {
        let parentNode = map.get(parent);
        if (!parentNode) {
            parentNode = new TreeNode(parent);
            map.set(parent, parentNode);
        }

        let childNode = map.get(child);
        if (!childNode) {
            childNode = new TreeNode(child);
            map.set(child, childNode);
        }

        if (isLeft) {
            parentNode.left = childNode;
        } else {
            parentNode.right = childNode;
        }
        parentMap.set(child, parent);
    }

    let root = descriptions[0][0];

    while (parentMap.has(root)) {
        root = parentMap.get(root);
    }

    return map.get(root);
};