Project: syntax-tree/unist-util-filter

Package: unist-util-filter@4.0.0

  1. Dependents: 0
  2. unist utility to create a new tree with nodes that pass a filter
  1. util 146
  2. utility 142
  3. unist 130
  4. tree 44
  5. ast 36
  6. unist-util 25
  7. node 25
  8. test 6
  9. filter 5


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


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.


This package is ESM only. In Node.js (version 14.14+ and 16.0+), 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'


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})


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


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

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

Create a new tree of copies of all nodes that pass test.

The tree is walked in preorder (NLR), visiting the node itself, then its head, etc.


New filtered tree (Node or null).

null is returned if tree itself didn’t pass the test, or is cascaded away.


Configuration (TypeScript type).



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


Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 14.14+ and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.


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.


MIT © Eugene Sharygin