Nested sets

nested_sets.js

var data = [
  {
    title: "Одежда",
    left: 1,
    right: 22
  },
  {
    title: "Мужская",
    left: 2,
    right: 9
  },
  {
    title: "Женская",
    left: 10,
    right: 21
  },
  {
    title: "Костюмы",
    left: 3,
    right: 8
  },
  {
    title: "Платья",
    left: 11,
    right: 16
  },
  {
    title: "Юбки",
    left: 17,
    right: 18
  },
  {
    title: "Блузы",
    left: 19,
    right: 20
  },
  {
    title: "Брюки",
    left: 4,
    right: 5
  },
  {
    title: "Жакеты",
    left: 6,
    right: 7
  },
  {
    title: "Вечерние",
    left: 12,
    right: 13
  },
  {
    title: "Летние",
    left: 14,
    right: 15
  }
]

const walk = data => {
  if (!data) return;
  for (let i = 0; i < data.length; i++) {
    for (let l = 0; l < data.length; l++) {
      if (data[l].left > data[i].left && data[l].right < data[i].right) {
        data[i].children = data[i].children || []
        data[i].children.push(data.splice(l, 1)[0])
        l--
      }
    }
    delete data[i].left
    delete data[i].right
    walk(data[i].children)
  }
  return data
}

let tree = walk(data)

const flatty = (tree, counter) => {
  let result = []
  counter = counter || { index: 1 }
  for (let i = 0; i < tree.length; i++) {
    result.push(tree[i])
    tree[i].left = counter.index++
    if (tree[i].children) {
      result = result.concat(flatty(tree[i].children, counter))
      delete tree[i].children
    }
    tree[i].right = counter.index++
  }
  return result
}

let flat = flatty(tree)