Function dfs

javascript/0938-range-sum-of-bst.js:22–27

(node)

    let total = 0;

    const dfs = (node) => {
        if (!node) return;
        if (node.val >= low && node.val <= high) total += node.val;
        dfs(node.left);
        dfs(node.right);
    };
    dfs(root);
    return total;
};