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unist-util-filter

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

Contents

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 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'
</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 of copies of all nodes that pass test.

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

Parameters
  • tree (Node) — tree to filter
  • options (Options, optional) — configuration
  • test (Test, optional) — unist-util-is compatible test
Returns

New filtered tree (Node or null).

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

Options

Configuration (TypeScript type).

Fields
  • cascade (boolean, default: true) — whether to drop parent nodes if they had children, but all their children were filtered out

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 14.14+ and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

Related

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

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