删除二叉树节点

function remove (root, key) {
    if (root == null){
        return null;
    }
    var  current = root;
    if (current.key > key) {
        current.left = remove(current.left);
        return current.left;
    }
    else if (current.key < key) {
        current.right = remove(current.right);
        return current.right;
    } else {
        //只有一边有孩子或者没有孩子的情况
        if (current.left == null) {
            var rightNode = current.right;
            return rightNode;
        }
        //只有一边有孩子或者没有孩子的情况
        if (current.right == null) {
            var leftNode = current.left;
            return leftNode;
        }
        //寻找最小值
        var rightNode = current.right;
        while(rightNode.left) {
            rightNode = rightNode.left
            if(rightNode.left.left == null) {
                // 删除最小值
                rightNode.left = null;
            }
        }
        rightNode.right = current.right;
        rightNode.left = current.left;
        return rightNode;
    }
}