right-rotate.js

function rightRotate(root) {
  let pivot = root.left;
  if (pivot.right) {
    //establish right to be child of root's parent.
    pivot.right.parent.node = root;
    pivot.right.parent.side = 'left';
  }
  root.left = pivot.right;
  pivot.parent.node = root.parent.node;
  (root.parent.node) ? root.parent.node[root.parent.side] = pivot: pivot.parent.side = '';
  root.parent.node = pivot;
  root.parent.side = 'right';
  pivot.right = root;
}