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https://github.com/syntax-tree/unist-util-parents

unist utility to add references to parents on nodes in a tree
https://github.com/syntax-tree/unist-util-parents

parent syntax-tree unist unist-util util

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unist utility to add references to parents on nodes in a tree

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README 

        
# unist-util-parents



[![Build][build-badge]][build]

[![Coverage][coverage-badge]][coverage]

[![Downloads][downloads-badge]][downloads]

[![Size][size-badge]][size]

[![Sponsors][sponsors-badge]][collective]

[![Backers][backers-badge]][collective]

[![Chat][chat-badge]][chat]



[unist][] utility to add references to parents on nodes in a tree.



## Contents



*   [What is this?](#what-is-this)

*   [When should I use this?](#when-should-i-use-this)

*   [Install](#install)

*   [Use](#use)

*   [API](#api)

    *   [`parents(tree)`](#parentstree)

    *   [`Proxy`](#proxy)

*   [Types](#types)

*   [Compatibility](#compatibility)

*   [Related](#related)

*   [Contribute](#contribute)

*   [License](#license)



## What is this?



This utility creates a proxy of the tree that acts like the original tree upon

reading, but each proxied node has a reference to its parent node.



## When should I use this?



This package can be very useful for problems where it is needed to figure out

what a nodes ancestors are, because unist itself is a non-cyclical data

structure, and thus does not provide that information.

On the other hand, this info on ancestors can also be gathered when walking the

tree with [`unist-util-visit-parents`][unist-util-visit-parents].



## Install



This package is [ESM only][esm].

In Node.js (version 16+), install with [npm][]:



```sh

npm install unist-util-parents

```



In Deno with [`esm.sh`][esmsh]:



```js

import {parent} from 'https://esm.sh/unist-util-parents@3'

```



In browsers with [`esm.sh`][esmsh]:



```html



  import {parent} from 'https://esm.sh/unist-util-parents@3?bundle'



```



## Use



```js

import {u} from 'unist-builder'

import {parents} from 'unist-util-parents'



const tree = u('root', [

  u('leaf', 'leaf 1'),

  u('node', [

    u('leaf', 'leaf 2'),

    u('void'),

    u('node', [

      u('leaf', 'leaf 3'),

      u('node', [u('leaf', 'leaf 4')]),

      u('void'),

      u('leaf', 'leaf 5')

    ])

  ])

])



const wrapped = parents(tree)



// Leaf 4

const node = wrapped.children[1].children[2].children[1].children[0]



const chain = []

while (node) {

  chain.push(node.type)

  node = node.parent

}



console.log(chain.reverse())

```



Yields:



```js

['root', 'node', 'node', 'node', 'leaf']

```



## API



This package exports the identifier [`parents`][api-parents].

There is no default export.



### `parents(tree)`



Create a proxy of `tree` that acts like the original tree upon reading, but

each proxied node has a reference to its parent node.



###### Notes



The returned proxy imposes two additional fields on all of its nodes:



*   `parent` — parent link (or `undefined` for the root)

*   `node` — link to the original node



These new fields are not enumerable and the original tree is *not changed*.

This means you can use `JSON.stringify` on the wrapped tree and it’s the same.



`wrapped.children` returns array of wrapped child nodes, so that any recursive

algorithm will work on a wrapped tree just as well.



To write changes to the tree, use `.node` to access the original tree.



###### Parameters



*   `tree` ([`Node`][node])

    — tree to proxy



###### Returns



Proxy of `tree` ([`Proxy`][api-proxy]).



### `Proxy`



A proxy of a [`Node`][node] that adds two additional fields:



*   `parent` — parent link (or `undefined` for the root)

*   `node` — link to the original node



## Types



This package is fully typed with [TypeScript][].

It exports the additional type [`Proxy`][api-proxy].



## Compatibility



Projects maintained by the unified collective are compatible with maintained

versions of Node.js.



When we cut a new major release, we drop support for unmaintained versions of

Node.

This means we try to keep the current release line, `unist-util-parents@^3`,

compatible with Node.js 16.



## Related



*   [`unist-util-visit-parents`][unist-util-visit-parents]

    — walk the tree with ancestral information



## Contribute



See [`contributing.md`][contributing] in [`syntax-tree/.github`][health] for

ways to get started.

See [`support.md`][support] for ways to get help.



This project has a [code of conduct][coc].

By interacting with this repository, organisation, or community you agree to

abide by its terms.



## License



[MIT][license] © Eugene Sharygin



[build-badge]: https://github.com/syntax-tree/unist-util-parents/workflows/main/badge.svg



[build]: https://github.com/syntax-tree/unist-util-parents/actions



[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/unist-util-parents.svg



[coverage]: https://codecov.io/github/syntax-tree/unist-util-parents



[downloads-badge]: https://img.shields.io/npm/dm/unist-util-parents.svg



[downloads]: https://www.npmjs.com/package/unist-util-parents



[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=unist-util-parents



[size]: https://bundlejs.com/?q=unist-util-parents



[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg



[backers-badge]: https://opencollective.com/unified/backers/badge.svg



[collective]: https://opencollective.com/unified



[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg



[chat]: https://github.com/syntax-tree/unist/discussions



[npm]: https://docs.npmjs.com/cli/install



[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c



[esmsh]: https://esm.sh



[typescript]: https://www.typescriptlang.org



[license]: license



[health]: https://github.com/syntax-tree/.github



[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md



[support]: https://github.com/syntax-tree/.github/blob/main/support.md



[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md



[unist]: https://github.com/syntax-tree/unist



[node]: https://github.com/syntax-tree/unist#node



[unist-util-visit-parents]: https://github.com/syntax-tree/unist-util-visit-parents



[api-parents]: #parentstree



[api-proxy]: #proxy