unist-util-filter

unist utility to create a new tree with only nodes that pass a test.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • filter(tree[, options][, test])
• Types
• Compatibility
• Related
• Contribute
• License

What is this?

This is a small utility that helps you clean a tree.

When should I use this?

You can use this utility to remove things from a tree. This utility is very similar to unist-util-remove, which changes the given tree. Modifying a tree like that utility does is much faster on larger documents.

You can also walk the tree with unist-util-visit to remove nodes. To create trees, use unist-builder.

Install

This package is ESM only. In Node.js (version 12.20+, 14.14+, 16.0+, 18.0+), install with npm:

npm install unist-util-filter

In Deno with esm.sh:

import {filter} from "https://esm.sh/unist-util-filter@4"

In browsers with esm.sh:

<script type="module">
  import {filter} from "https://esm.sh/unist-util-filter@4?bundle"
</script>

Use

import {u} from 'unist-builder'
import {filter} from 'unist-util-filter'

const tree = u('root', [
  u('leaf', '1'),
  u('parent', [u('leaf', '2'), u('parent', [u('leaf', '3')])]),
  u('leaf', '4')
])

const newTree = filter(tree, node => node.type !== 'leaf' || node.value % 2 === 0)

console.dir(newTree, {depth: null})

Yields:

{
  type: 'root',
  children: [
    {type: 'parent', children: [{type: 'leaf', value: '2'}]},
    {type: 'leaf', value: '4'}
  ]
}

API

This package exports the identifier filter. There is no default export.

filter(tree[, options][, test])

Create a new tree (Node) of copies of all nodes that pass test. (Test from unist-util-is). The tree is walked in preorder (NLR), visiting the node itself, then its head, etc.

options

Configuration (optional).

options.cascade

Whether to drop parent nodes if they had children, but all their children were filtered out (boolean, default: true).

Returns

New filtered tree (Node?). null is returned if tree itself didn’t pass the test, or is cascaded away.

Types

This package is fully typed with TypeScript. It exports the additional type Options.

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

• unist-util-visit — walk the tree
• unist-util-visit-parents — walk the tree with a stack of parents
• unist-util-map — create a new tree with all nodes mapped by a given function
• unist-util-flatmap — create a new tree by mapping (to an array) by a given function
• unist-util-remove — remove nodes from a tree that pass a test
• 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, organization, or community you agree to abide by its terms.

License

MIT © Eugene Sharygin