unist-util-map

What is unist-util-map?

The unist-util-map package is a utility for transforming unist syntax trees by applying a function to each node, creating a new tree with the same structure but with transformed nodes.

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

Transforming Nodes

This feature allows you to apply a transformation function to each node in a unist tree. In the example, each text node's value is transformed to uppercase.

const map = require('unist-util-map');

const tree = {
  type: 'root',
  children: [
    { type: 'text', value: 'Hello' },
    { type: 'text', value: 'World' }
  ]
};

const newTree = map(tree, node => {
  if (node.type === 'text') {
    return { ...node, value: node.value.toUpperCase() };
  }
  return node;
});

console.log(newTree);

Other packages similar to unist-util-map

unist-util-visit

unist-util-visit is a utility for walking through unist syntax trees and performing operations on nodes. Unlike unist-util-map, which creates a new tree with transformed nodes, unist-util-visit is typically used for side effects or gathering information from nodes.

unist-util-filter

unist-util-filter is used to create a new tree by filtering nodes based on a predicate function. While unist-util-map transforms nodes, unist-util-filter removes nodes that do not match the predicate.

unist-util-modify-children

unist-util-modify-children allows for modifying the children of a node in a unist tree. It is more focused on direct modifications rather than creating a new tree structure like unist-util-map.

README

unist-util-map

unist utility to create a new tree by mapping all nodes with the given function.

Install

npm:

npm install unist-util-map

Usage

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

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

var next = map(tree, function(node) {
  return node.type === 'leaf'
    ? Object.assign({}, node, {value: 'CHANGED'})
    : node
})

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

Yields:

{
  type: 'tree',
  children: [
    { type: 'leaf', value: 'CHANGED' },
    { type: 'node', children: [ { type: 'leaf', value: 'CHANGED' } ] },
    { type: 'void' },
    { type: 'leaf', value: 'CHANGED' }
  ]
}

…note that tree is not mutated.

API

map(tree, mapFn)

Create a new tree by mapping all nodes with the given function.

Parameters

• tree (Node) — Tree to map
• callback (Function) — Function that returns a new node

Returns

Node — New mapped tree.

function mapFn(node[, index, parent])

Function called with a node to produce a new node.

Parameters

• node (Node) — Current node being processed
• index (number?) — Index of node, or null
• parent (Node?) — Parent of node, or null

Returns

Node — Node to be used in the new tree. Its children are not used: if the original node has children, those are mapped.

Related

• unist-util-filter — Create a new tree with all nodes that pass the given function
• unist-util-flatmap — Create a new tree by expanding a node into many
• unist-util-remove — Remove nodes from trees
• unist-util-select — Select nodes with CSS-like selectors
• unist-util-visit — Recursively walk over nodes
• unist-builder — Creating trees

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 © azu