Flat To Tree

Convert flat array into tree structure. O(n) time complexity.

Installation

npm i flat-to-tree

Example

import flatToTree from "flat-to-tree";

const flat = [
  {
    id: 2,
    parentId: 1,
    title: "node-1-2" // any properties
  },
  {
    id: 3,
    parentId: 2,
    title: "node-1-2-3"
  },
  {
    id: 1,
    parentId: null,
    title: "root"
  }
];

const tree = flatToTree(flat);

/*
tree: 
[
  {
    id: 1,
    parentId: null,
    title: "root",
    children: [
      {
        id: 2,
        parentId: 1,
        title: "node-1-2",
        children: [
          {
            id: 3,
            parentId: 2,
            title: "node-1-2-3",
            children: []
          }
        ]
      }
    ]
  }
];
*/

const flat2 = [
  {
    key: 2,
    pId: 1,
    name: "node-1-2" // any properties
  },
  {
    key: 3,
    pId: 2,
    name: "node-1-2-3"
  },
  {
    key: 1,
    pId: null,
    name: "root"
  }
];

const tree2 = flatToTree(flat2, {
  id: "key",
  parentId: "pId",
  children: "sub"
});

/*
tree2: 
[
  {
    key: 1,
    pId: null,
    title: "root",
    sub: [
      {
        key: 2,
        pId: 1,
        title: "node-1-2",
        sub: [
          {
            key: 3,
            pId: 2,
            title: "node-1-2-3",
            sub: []
          }
        ]
      }
    ]
  }
];
*/

const flat3 = [
  {
    id: 2,
    parentId: 1,
    title: "node-1-2"
  },
  {
    id: 1,
    parentId: 10, // not exist, will be considered as root nodes
    title: "root-1"
  },
  {
    id: 4,
    parentId: 10, // not exist, will be considered as root nodes
    title: "root-4"
  },
  {
    id: 3,
    parentId: 2,
    title: "node-1-2-3"
  }
];

const tree3 = flatToTree(flat3);

/*
tree3: 
[
  {
    children: [
      {
        children: [{ children: [], id: 3, parentId: 2, title: "node-1-2-3" }],
        id: 2,
        parentId: 1,
        title: "node-1-2"
      }
    ],
    id: 1,
    parentId: 10,
    title: "root-1"
  },
  { children: [], id: 4, parentId: 10, title: "root-4" }
]
*/

API

flatToTree(data, [options])

Parameters

• data: Array: Flat array to convert
• options?: Object: Config options:
  • id?: String : Property name of unique node identifier. Default: 'id'.
  • parentId?: String : Property name of parent node id. Default: 'parentId'.
  • children?: String : Property name of an array to store child nodes. Default: 'children'.

Return

• Array: Converted tree structure

Browser compatibility

• Chrome 61+

Use Babel for better browser support