unist-util-filter

What is unist-util-filter?

The `unist-util-filter` package is a utility for filtering nodes in a Unist syntax tree. It allows you to traverse and selectively remove nodes based on a predicate function, making it useful for tasks such as cleaning up or transforming abstract syntax trees (ASTs).

What are unist-util-filter's main functionalities?

Filter nodes based on a predicate

This feature allows you to filter nodes in a Unist tree based on a predicate function. In this example, the tree is filtered to remove paragraphs containing the text 'World'.

const filter = require('unist-util-filter');
const tree = {
  type: 'root',
  children: [
    { type: 'paragraph', children: [{ type: 'text', value: 'Hello' }] },
    { type: 'paragraph', children: [{ type: 'text', value: 'World' }] }
  ]
};
const filteredTree = filter(tree, node => node.type !== 'paragraph' || node.children[0].value !== 'World');
console.log(filteredTree);

Filter nodes with a specific type

This feature allows you to filter out nodes of a specific type. In this example, all 'heading' nodes are removed from the tree.

const filter = require('unist-util-filter');
const tree = {
  type: 'root',
  children: [
    { type: 'paragraph', children: [{ type: 'text', value: 'Hello' }] },
    { type: 'heading', children: [{ type: 'text', value: 'Title' }] }
  ]
};
const filteredTree = filter(tree, node => node.type !== 'heading');
console.log(filteredTree);

Other packages similar to unist-util-filter

unist-util-visit

The `unist-util-visit` package is used for traversing Unist syntax trees. Unlike `unist-util-filter`, which removes nodes based on a predicate, `unist-util-visit` allows you to visit nodes and perform actions on them. It is more focused on traversal and manipulation rather than filtering.

unist-util-map

The `unist-util-map` package allows you to transform nodes in a Unist tree by applying a function to each node. While `unist-util-filter` is used for removing nodes, `unist-util-map` is used for transforming nodes, making it useful for different kinds of tree manipulations.

unist-util-remove

The `unist-util-remove` package is specifically designed for removing nodes from a Unist tree based on a predicate. It is similar to `unist-util-filter` but focuses solely on the removal aspect, without the additional filtering capabilities.

README

unist-util-filter

unist utility to create a new tree with all nodes that pass the given test.

Install

npm:

npm install unist-util-filter

Use

var u = require('unist-builder')
var filter = require('unist-util-filter')

var tree = u('root', [
  u('leaf', '1'),
  u('node', [u('leaf', '2'), u('node', [u('leaf', '3')])]),
  u('leaf', '4')
])

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

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

Yields:

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

API

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

Create a new tree consisting 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.cascade (boolean, default: true) — Whether to drop parent nodes if they had children, but all their children were filtered out
• test (Test, optional) — is-compatible test (such as a type)

Returns

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

Related

• unist-util-visit — Recursively walk over nodes
• unist-util-visit-parents — Like visit, but 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