unist-util-index

unist utility to create a mutable index mapping property values or computed keys back to nodes.

Install

This package is ESM only: Node 12+ is needed to use it and it must be imported instead of required.

npm:

npm install unist-util-index

Use

import fs from 'fs'
import remark from 'remark'
import toString from 'mdast-util-to-string'
import {Index} from 'unist-util-index'

// Parse and read this repo’s readme:
var tree = remark.parse(fs.readFileSync('readme.md'))

// Index on heading depth:
var index = new Index('depth', tree, 'heading')

console.log(index.get(2).map(toString))

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

console.log(index.get('unist').map(node => node.url))

Yields:

[ 'Install', 'Use', 'API', 'Related', 'Contribute', 'License' ]
[ 'https://github.com/syntax-tree/unist' ]

API

This package exports the following identifiers: Index. There is no default export.

class Index(prop|keyFn[, tree[, test]])

Create an index data structure that maps keys (calculated by keyFn function or the values at prop in each node) to a list of nodes.

If tree is given, the index is initialized with all nodes, optionally filtered by test.

Parameters

• prop (string) — Property to look up in each node to find keys
• keyFn (Function) — Function called with each node to calculate keys
• tree (Node?) — Tree to index
• test (Test, optional) — is-compatible test (such as a type)

Returns

Index — an index instance.

function keyFn(node)

Function called with every added node to return the key to index on.

Index#get(key)

Get nodes by key (*). Returns a list of zero or more nodes (Array.<Node>).

Index#add(node)

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

Index#remove(node)

Remove node from the index (if present).

Related

• unist-util-is — Utility to check if a node passes a test
• unist-util-visit — Utility to recursively walk over nodes
• unist-util-map — Create a new tree by mapping by the provided function
• unist-util-flatmap — Create a new tree by mapping and then flattening
• unist-util-select — Select nodes with CSS-like selectors

Contribute

See contributing.md in syntax-tree/.github for ways to get started. See support.md for ways to get help.

This project has a Code of Conduct. By interacting with this repository, organisation, or community you agree to abide by its terms.

License

MIT © Eugene Sharygin