Find mirror of a given node in Binary tree

<script>

// Javascript program to find the mirror
// Node in Binary tree 

/* A binary tree Node has data, pointer
to left child and a pointer to right child */
class Node 
{
    
    // Create new Node and initialize it 
    constructor(key)
    {
        this.key = key;
        this.left = this.right = null;
    }
}

// Recursive function to find mirror of Node 
function findMirrorRec(target, left, right)
{
    
    /* If any of the Node is none then Node itself 
    and descendant have no mirror, so return 
    none, no need to further explore! */
    if (left == null || right == null) 
        return 0; 
  
    /* If left Node is target Node, then return 
    right's key (that is mirror) and vice 
    versa */
    if (left.key == target) 
        return right.key; 
  
    if (right.key == target) 
        return left.key; 
  
    // First recur external Nodes 
    let mirror_val = findMirrorRec(
        target, left.left, right.right); 
    if (mirror_val != 0) 
        return mirror_val; 
  
    // If no mirror found, recur internal Nodes 
    return findMirrorRec(target, left.right, 
                                 right.left); 
}

// Interface for mirror search 
function findMirror(root, target)
{
    if (root == null) 
        return 0; 
    if (root.key == target) 
        return target; 
        
    return findMirrorRec(target, root.left, 
                                 root.right); 
}

// Driver code
let root = new Node(1); 
root.left = new Node(2); 
root.left.left = new Node(4); 
root.left.left.right = new Node(7); 
root.right = new Node(3); 
root.right.left = new Node(5); 
root.right.right = new Node(6); 
root.right.left.left = new Node(8); 
root.right.left.right = new Node(9); 

// Target Node whose mirror have to be searched 
let target = root.left.left.key; 

let mirror = findMirror(root, target); 

if (mirror != 0) 
    document.write("Mirror of Node " + target +
                   " is Node " + mirror + "<br>");
else
    document.write("Mirror of Node " + target + 
                   " is null " + "<br>");

// This code is contributed by rag2127

</script>

// JavaScript program to find the mirror Node
// in Binary tree 

/* A binary tree Node has data, 
pointer to left child and 
a pointer to right child */
class Node {
    constructor(key) {
        this.key = key;
        this.left = null;
        this.right = null;
    }
}

let target_level = -1;
let target_position = -1;
let mirror = 0;
function findMirror(root, target, level, position) {
    if (!root) return;

    // If node is target node
    if (root.key == target) {
        target_level = level;
        target_position = position;
        return;
    }

    // Checking if target has found then check for mirror
    if (target_level != -1 && level == target_level && (Math.abs(position) ==   Math.abs(target_position))) {
        mirror = root.key;
        return;
    }

    // Going left side of the node
    findMirror(root.left, target, level + 1, position - 1);

    // Going right side of the node
    findMirror(root.right, target, level + 1, position + 1);
}

// Driver Code
let root = new Node(1);
root.left = new Node(2);
root.left.left = new Node(4);
root.left.left.right = new Node(7);
root.right = new Node(3);
root.right.left = new Node(5);
root.right.right = new Node(6);
root.right.left.left = new Node(8);
root.right.left.right = new Node(9);

// Target Node whose mirror have to be searched 
let target = root.left.left.key;

findMirror(root, target, 0, 0);
if (mirror != 0) {
    console.log(`Mirror of Node ${target} is Node ${mirror}`);
} else {
    console.log(`Mirror of Node ${target} is NULL!`);
}