unist-util-index
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!Chatchat-badgechatunist utility to create an index from certain nodes.
Contents
* [`Index(prop|keyFunction[, tree[, test]])`](#indexpropkeyfunction-tree-test)
* [`KeyFunction`](#keyfunction)
* [`Test`](#test)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 onlyesm. In Node.js (version 14.14+ and 16.0+), install with npm:npm install unist-util-indexIn Deno with
esm.shesmsh:import {Index} from 'https://esm.sh/unist-util-index@3'In browsers with
esm.shesmsh:<script type="module">
import {Index} from 'https://esm.sh/unist-util-index@3?bundle'
</script>Use
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((d) => toString(d)))
// Index on definition identifier:
const indexOnIdentifier = new Index('identifier', tree, 'definition')
console.log(indexOnIdentifier.get('unist').map((node) => node.url))Yields:
[
'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 identifierIndexindex.
There is no default export.Index(prop|keyFunction[, tree[, test]])
Create a mutable index data structure, that maps property values or computed
keys, to nodes.If
tree is given, the index is initialized with all nodes, optionally
filtered by test.Parameters
prop(string)
— field to look up in each node to find keyskeyFunction(KeyFunctionkeyfunction)
— function called with each node to calculate keys— tree to index— `unist-util-is` compatible testReturns
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>node).Index#add(node)
Add node to the index (if not already present).Parameters
— node to indexReturns
Current instance (Index).Index#remove(node)
Remove node from the index (if present).Parameters
— node to removeReturns
Current instance (Index).KeyFunction
Function called with every added node to calculate the key to index on
(TypeScript type).Parameters
— node to calculate a key forReturns
Key to index on (unknown).Can be anything that can be used as a key in a
Mapmap.Test
unist-util-isunist-util-is compatible test (TypeScript type).Types
This package is fully typed with TypeScript. It exports the additional typesKeyFunctionkeyfunction and
Testtest.Compatibility
Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, 16.0+, and 18.0+. Our projects sometimes work with older versions, but this is not guaranteed.Related
— utility to check if a node passes a test— utility to recursively walk over nodes— select nodes with CSS-like selectorsContribute
Seecontributing.mdcontributing in syntax-tree/.githubhealth for
ways to get started.
See support.mdsupport for ways to get help.This project has a Code of Conductcoc. By interacting with this repository, organisation, or community you agree to abide by its terms.
