Subtree of Another Tree

Problem statement

Given the roots of two binary trees root and subRoot, return true if there is a subtree of root with the same structure and node values of subRoot and false otherwise.

A subtree of a binary tree tree is a tree that consists of a node in tree and all of this node's descendants. The tree tree could also be considered as a subtree of itself.

Example 1:

Input: root = [3,4,5,1,2], subRoot = [4,1,2]Output: true

Example 2:

Input: root = [3,4,5,1,2,null,null,null,null,0], subRoot = [4,1,2]Output: false

Constraints:

• The number of nodes in the root tree is in the range [1, 2000].
• The number of nodes in the subRoot tree is in the range [1, 1000].
• -104 <= root.val <= 104
• -104 <= subRoot.val <= 104

My solution

/**
 * 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 {TreeNode} root
 * @param {TreeNode} subRoot
 * @return {boolean}
 */
var isSubtree = function(root, subRoot) {
    if (root === null && subRoot === null) {
        return true
    } else if (root === null || subRoot === null) {
        return false
    } else if (checkIfIdentical(root, subRoot)) {
        return true
    } else {
        return isSubtree(root.left, subRoot) || isSubtree(root.right, subRoot)
    }
};

function checkIfIdentical(root, subRoot) {
    // console.log(root, subRoot)
    if (root === null && subRoot === null) {
        return true
    } else if (root === null || subRoot === null) {
        return false
    } else {
        return root.val === subRoot.val && checkIfIdentical(root.left, subRoot.left) && checkIfIdentical(root.right, subRoot.right)
    }
    
}