Performant array to tree
Converts an array of items with ids and parent ids to a nested tree in a performant way (time complexity O(n)
). Runs in browsers and node.
Why another package
Other packages have stricter assumptions or are not as performant, as they often use nested loops or recursion. For example:
o-unflatten requires the input to be ordered such that parent nodes always come before their children.
un-flatten-tree uses 2 nested loops (time complexity O(n^2)
).
This implementation does not require any order of items in the input array and focuses on runtime performance. It is the fastest amongst 4 different packages, you can find the benchmarks here. It uses an index and a single loop (time complexity O(n)
). It was inspired by this discussion on StackOverflow.
Installation
yarn add performant-array-to-tree
or if using npm
npm install --save performant-array-to-tree
Usage
const tree = arrayToTree([
{ id: "4", parentId: null, custom: "abc" },
{ id: "31", parentId: "4", custom: "12" },
{ id: "1941", parentId: "418", custom: "de" },
{ id: "1", parentId: "418", custom: "ZZZz" },
{ id: "418", parentId: null, custom: "ü" },
]);
Which results in the following array:
[
{
data: { id: "4", parentId: null, custom: "abc" },
children: [
{ data: { id: "31", parentId: "4", custom: "12" }, children: [] },
],
},
{
data: { id: "418", parentId: null, custom: "ü" },
children: [
{ data: { id: "1941", parentId: "418", custom: "de" }, children: [] },
{ data: { id: "1", parentId: "418", custom: "ZZZz" }, children: [] },
],
},
];
Configuration
You can provide a second argument to arrayToTree with configuration options. Right now, you can set the following:
id
: Key of the id field of the item. Also works with nested properties (e. g. "nested.parentId"
). Default: "id"
.parentId
: Key of the parent's id field of the item. Also works with nested properties (e. g. "nested.parentId"
). Default: "parentId"
.nestedIds
: Option to enable/disable nested ids. Default: true
.childrenField
: Key which will contain all child nodes of the parent node. Default: "children"
dataField
: Key which will contain all properties/data of the original items. Set to null if you don't want a container. Default: "data"
throwIfOrphans
: Option to throw an error if the array of items contains one or more items that have no parents in the array or if the array of items contains items with a circular parent/child relationship. This option has a small runtime penalty, so it's disabled by default. When enabled, the function will throw an error containing the parentIds that were not found in the items array, or in the case of only circular item relationships a generic error. The function will throw an error if the number of nodes in the tree is smaller than the number of nodes in the original array. When disabled, the function will just ignore orphans and circular relationships and not add them to the tree. Default: false
rootParentIds
: Object with parent ids as keys and true
as values that should be considered the top or root elements of the tree. This is useful when your tree is a subset of full tree, which means there is no item whose parent id is one of undefined
, null
or ''
. The array you pass in will be replace the default value. undefined
and null
are always considered to be rootParentIds. For more details, see #23. Default: {'': true}
assign
: Option that enables Object.assign
instead of the spread operator to create an item in the tree when dataField
is null
. This is useful if your items have a prototype that should be maintained. If enabled and dataField
is null
, the original node item will be used, and the children
property will be assigned, calling any setters on that field. If dataField
is not null
, this option has no effect, since the original node will be used under the dataField
of a new object. If you are unsure whether you need to enable this, it's likely fine to leave it disabled. Default: false
Example:
const tree = arrayToTree(
[
{ num: "4", ref: null, custom: "abc" },
{ num: "31", ref: "4", custom: "12" },
{ num: "1941", ref: "418", custom: "de" },
{ num: "1", ref: "418", custom: "ZZZz" },
{ num: "418", ref: null, custom: "ü" },
],
{ id: "num", parentId: "ref", childrenField: "nodes" }
);
Which produces:
[
{
data: { num: "4", ref: null, custom: "abc" },
nodes: [{ data: { num: "31", ref: "4", custom: "12" }, nodes: [] }],
},
{
data: { num: "418", ref: null, custom: "ü" },
nodes: [
{ data: { num: "1941", ref: "418", custom: "de" }, nodes: [] },
{ data: { num: "1", ref: "418", custom: "ZZZz" }, nodes: [] },
],
},
];
Example with no data field:
const tree = arrayToTree(
[
{ id: "4", parentId: null, custom: "abc" },
{ id: "31", parentId: "4", custom: "12" },
{ id: "1941", parentId: "418", custom: "de" },
{ id: "1", parentId: "418", custom: "ZZZz" },
{ id: "418", parentId: null, custom: "ü" },
],
{ dataField: null }
);
Which produces:
[
{
id: "4",
parentId: null,
custom: "abc",
children: [{ id: "31", parentId: "4", custom: "12", children: [] }],
},
{
id: "418",
parentId: null,
custom: "ü",
children: [
{ id: "1941", parentId: "418", custom: "de", children: [] },
{ id: "1", parentId: "418", custom: "ZZZz", children: [] },
],
},
];
Example with nested id/parentId properties:
const tree = arrayToTree(
[
{ num: { id: "4" }, parent: { parentId: null }, custom: "abc" },
{ num: { id: "31" }, parent: { parentId: "4" }, custom: "12" },
],
{ id: "num.id", parentId: "parent.parentId" }
);
Which produces:
[
{
data: { num: { id: "4" }, parent: { parentId: null }, custom: "abc" },
children: [
{
data: { num: { id: "31" }, parent: { parentId: "4" }, custom: "12" },
children: [],
},
],
},
];
TypeScript
This project includes types, just import the module as usual:
import { arrayToTree } from "performant-array-to-tree";
const tree = arrayToTree(array);
Development
yarn version
to create a new version
npm login
npm publish --access public
to publish it to npm