Subtree of Another Tree

subTree.js

function isSubtree(s, t) {
  const queue = [s];

  while (queue.length > 0) {
    const node = queue.shift();

    if (isSame(node, t)) {
      return true;
    } else {
      if (node.left) {
        queue.push(node.left);
      }

      if (node.right) {
        queue.push(node.right);
      }
    }
  }

  return false;
}

function isSame(l, r) {
  if (!l && !r) {
    return true;
  } else if (l && r) {
    const lVal = l.val;
    const rVal = r.val;

    return lVal === rVal && isSame(l.left, r.left) && isSame(l.right, r.right);
  } else {
    return false;
  }
}