Build tree array from flat array in javascript

tree_from_array.js

const createDataTree = dataset => {
  const hashTable = Object.create(null);
  dataset.forEach(aData => hashTable[aData.ID] = {...aData, childNodes: []});
  const dataTree = [];
  dataset.forEach(aData => {
    if(aData.parentID) hashTable[aData.parentID].childNodes.push(hashTable[aData.ID])
    else dataTree.push(hashTable[aData.ID])
  });
  return dataTree;
};