TransferValue and MergeNodes function

BTree.js

/**
 * btree namespace.
 * @type {BTree}
*/
export default class BTree {
  ...
  /**
   * Transfer one value from the origin to the target.
   * @param {BTreeNode} origin 
   * @param {BTreeNode} target 
  */
  transferValue(origin, target) {
    const indexo = origin.parent.children.indexOf(origin);
    const indext = origin.parent.children.indexOf(target);
    if (indexo < indext) {
      // Transfer value from parent to target
      target.addValue(target.parent.removeValue(indexo));
      // Transfer value from origin to parent
      origin.parent.addValue(origin.removeValue(origin.n-1));
    } else {
      // Transfer value from parent to target
      target.addValue(target.parent.removeValue(indext));
      // Transfer value from origin to parent
      origin.parent.addValue(origin.removeValue(0));
    }
  }
  /**
   * Merge 2 nodes into one
   * @param {BTreeNode} origin 
   * @param {BTreeNode} target 
  */
  mergeNodes(origin, target) {
    const indexo = origin.parent.children.indexOf(origin);
    const indext = target.parent.children.indexOf(target);
    // Add middle value of the parent into target node
    target.addValue(target.parent.removeValue(Math.min(indexo, indext)));
    // Add every value of origin into target node
    for (let i = origin.n - 1; i >= 0; i--) {
      target.addValue(origin.removeValue(i));
    }
    // Delete origin node reference
    target.parent.deleteChild(indexo);
  }
}