unist-util-index

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[unist][] utility to create an index from certain nodes.

* What is this?
* When should I use this?
* Install
* Use
* API
* [Index(prop|keyFunction[, tree[, test]])](#indexpropkeyfunction-tree-test)
* KeyFunction
* Test
* Types
* Compatibility
* Related
* Contribute
* License

What is this?

This utility creates a mutable index data structure, that maps property values
or computed keys, to nodes.
For example, you can use this to index all (footnote) definitions in a tree,
or all headings of a certain rank, to later retrieve them without having to walk
the tree each time.

When should I use this?

This is a utility that helps you deal with indexing the tree.
It’s pretty small, and you can definitely do it yourself, but this little
wrapper makes it all a bit easier.

Install

This package is [ESM only][esm].
In Node.js (version 16+), install with [npm][]:

``sh npm install unist-util-index`

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

`js import {Index} from 'https://esm.sh/unist-util-index@4'`

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

`html`

`Use`

`js import fs from 'node:fs/promises' import {fromMarkdown} from 'mdast-util-from-markdown' import {toString} from 'mdast-util-to-string' import {Index} from 'unist-util-index'

// Parse and read this repo’s readme: const tree = fromMarkdown(await fs.readFile('readme.md'))

// Index on heading depth: const indexOnDepth = new Index('depth', tree, 'heading')

console.log( indexOnDepth.get(2).map(function (d) { return toString(d) }) )

// Index on definition identifier: const indexOnIdentifier = new Index('identifier', tree, 'definition')

console.log( indexOnIdentifier.get('unist').map(function (node) { return node.url }) )`

Yields:

`js [ 'Contents', 'What is this?', 'When should I use this?', 'Install', 'Use', 'API', 'Types', 'Compatibility', 'Related', 'Contribute', 'License' ] [ 'https://github.com/syntax-tree/unist' ]`

`API`

This package exports the identifier [Index][index]. There is no default export.

`$3`

Create a mutable index data structure, that maps property values or computed keys, to nodes.

If treeis given, the index is initialized with all nodes, optionally filtered bytest.

###### Parameters

* prop (string) — field to look up in each node to find keys *keyFunction ([KeyFunction][keyfunction]) — function called with each node to calculate keys *tree ([Node][node], optional) — tree to index *test ([Test][test], optional) —unist-util-is compatible test

###### Returns

Instance (Index).

#### Index#get(key)

Get nodes by key.

###### Parameters

* key (unknown) — key to retrieve, can be anything that can be used as a key in a [Map][map]

###### Returns

List of zero or more nodes ([Array][node]).

#### Index#add(node)

Add node to the index (if not already present).

###### Parameters

* node ([Node][node]) — node to index

###### Returns

Current instance (Index).

#### Index#remove(node)

Remove node from the index (if present).

###### Parameters

* node ([Node][node]) — node to remove

###### Returns

Current instance (Index).

`$3`

Function called with every added node to calculate the key to index on (TypeScript type).

###### Parameters

* node ([Node][node]) — node to calculate a key for

###### Returns

Key to index on (unknown).

Can be anything that can be used as a key in a [Map][map].

`$3`

[unist-util-is][unist-util-is] compatible test (TypeScript type).

`Types`

This package is fully typed with [TypeScript][]. It exports the additional types [KeyFunction][keyfunction] and [Test][test].

`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-index@^4, compatible with Node.js 16.

`Related`

* unist-util-is— utility to check if a node passes a test *unist-util-visit— utility to recursively walk over nodes *unist-util-select— select nodes with CSS-like selectors

`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-index/workflows/main/badge.svg

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

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

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

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

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

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

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

[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

[map]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Map

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

[index]: #indexpropkeyfunction-tree-test

[keyfunction]: #keyfunction

[test]: #test

unist-util-index

[unist][] utility to create an index from certain nodes.

What is this?

When should I use this?

This is a utility that helps you deal with indexing the tree.
It’s pretty small, and you can definitely do it yourself, but this little
wrapper makes it all a bit easier.

Install

This package is [ESM only][esm].
In Node.js (version 16+), install with [npm][]:

``sh npm install unist-util-index`

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

`js import {Index} from 'https://esm.sh/unist-util-index@4'`

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

`html`

`Use`

`js import fs from 'node:fs/promises' import {fromMarkdown} from 'mdast-util-from-markdown' import {toString} from 'mdast-util-to-string' import {Index} from 'unist-util-index'

// Parse and read this repo’s readme: const tree = fromMarkdown(await fs.readFile('readme.md'))

// Index on heading depth: const indexOnDepth = new Index('depth', tree, 'heading')

console.log( indexOnDepth.get(2).map(function (d) { return toString(d) }) )

// Index on definition identifier: const indexOnIdentifier = new Index('identifier', tree, 'definition')

console.log( indexOnIdentifier.get('unist').map(function (node) { return node.url }) )`

Yields:

`js [ 'Contents', 'What is this?', 'When should I use this?', 'Install', 'Use', 'API', 'Types', 'Compatibility', 'Related', 'Contribute', 'License' ] [ 'https://github.com/syntax-tree/unist' ]`

`API`

This package exports the identifier [Index][index]. There is no default export.

`$3`

Create a mutable index data structure, that maps property values or computed keys, to nodes.

If treeis given, the index is initialized with all nodes, optionally filtered bytest.

###### Parameters

###### Returns

Instance (Index).

#### Index#get(key)

Get nodes by key.

###### Parameters

* key (unknown) — key to retrieve, can be anything that can be used as a key in a [Map][map]

###### Returns

List of zero or more nodes ([Array][node]).

#### Index#add(node)

Add node to the index (if not already present).

###### Parameters

* node ([Node][node]) — node to index

###### Returns

Current instance (Index).

#### Index#remove(node)

Remove node from the index (if present).

###### Parameters

* node ([Node][node]) — node to remove

###### Returns

Current instance (Index).

`$3`

Function called with every added node to calculate the key to index on (TypeScript type).

###### Parameters

* node ([Node][node]) — node to calculate a key for

###### Returns

Key to index on (unknown).

Can be anything that can be used as a key in a [Map][map].

`$3`

[unist-util-is][unist-util-is] compatible test (TypeScript type).

`Types`

This package is fully typed with [TypeScript][]. It exports the additional types [KeyFunction][keyfunction] and [Test][test].

`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-index@^4, compatible with Node.js 16.

`Related`

* unist-util-is— utility to check if a node passes a test *unist-util-visit— utility to recursively walk over nodes *unist-util-select— select nodes with CSS-like selectors

`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

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

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

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

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

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

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

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

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

[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

[map]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Map

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

[index]: #indexpropkeyfunction-tree-test

[keyfunction]: #keyfunction

[test]: #test