Non-recursive BST build from sorted array

sortedArrayToBST.js

export default function sortedArrayToBST(data) {
  let root = {};
  const Q = [root];
  const stack = [0, data.length - 1];

  while (Q.length !== 0) {
    const right = stack.pop();
    const left  = stack.pop();
    const cur   = Q.pop();

    const mid = left + ((right - left) >> 1);
    if (left - right === 0) {
      cur.data = data[mid];
    } else {
      if (left < mid) {
        cur.left = {};
        Q.push(cur.left); 
        stack.push(left, mid);
      }

      if (right > mid) {
        cur.right = {};
        Q.push(cur.right); 
        stack.push(mid + 1, right);
      }
    }
  }
  return root;
}