最適化されたレンダリングのためにキー値に基づいてオブジェクトの配列をネストする方法

[
  {
    tab: 'Results',
    section: '2017',
    title: 'Full year Results',
    description: 'Something here',
  },
  {
    tab: 'Results',
    section: '2017',
    title: 'Half year Results',
    description: 'Something here',
  },
  {
    tab: 'Reports',
    section: 'Marketing',
    title: 'First Report',
    description: 'Something here',
  }
]

[
  {
    tab: 'Results',
    sections: [
      {
        section: '2017',
        items: [
          { 'item that belongs here' },
          { ... }
        ]
      }
    ]
  },
  {
    tab: 'Reports',
    sections: [
      {
        section: 'Marketing',
        items: [
          { ... },
          { ... }
        ]
      }
    ]
  }
]

function groupAndMap(items, itemKey, childKey, predic) {
  return _.map(_.groupBy(items, itemKey), (obj, key) => ({
    [itemKey]: key,
    [childKey]: (predic && predic(obj)) || obj
  }));
}

const output = groupAndMap(items, "tab", "sections", arr =>
  groupAndMap(arr, "section", "items")
);