Как можно быстро перестроить дерево?

refactorCategories (categories) {
      let parents = this.findFirstParents(categories)

      parents.forEach(parent => {
        parent.children = this.findChildren(categories, parent.id)
      })
    },
    findChildren (array, id) {
      return array.filter(item => {
        return item.parent_id === id
      })
    },
    findFirstParents (categories) {
      return categories.filter(category => {
        return !category.parent_id
      })
    }

[
  id: 1,
  parent_id: null,
],
[
  id: 2,
  parent_id: null,
],
[
  id: 3,
  parent_id: null,
]

refactorCategories (categories) {
      console.log(this.getChildren(categories))
    },
    getChildren (categories, parentId = null) {
      categories.forEach(category => {
        if (category.parent_id === parentId) {
          category.children = this.getChildren(categories, category.parent_id)
        }
      })
      return categories
    }

refactorCategories (categories) {
      let parents = this.findFirstParents(categories)

      parents.forEach(parent => {
        parent.children = this.getChildren(categories, parent.id)
      })

      console.log(parents)
    },
    getChildren (categories, parentId) {
      return categories.filter(category => {
        return category.parent_id === parentId
      }).map(category => {
        category.children = this.getChildren(categories, category.id)
      })

data = [
    {id: 1, parent_id: null},
    {id: 2, parent_id: 1},
    {id: 3, parent_id: 2}];

tree = new Map();
for (node of data) {
    if (tree[node.parent_id] === undefined) {
        tree[node.parent_id] = [node.id]
    } else {
        tree[node.parent_id].push(node.id)
    }
}
console.log(tree);