unist-util-map
unist utility to create a new tree by mapping all nodes with a given function.
Contents
- What is this?
- When should I use this?
- Install
- Use
- API
- Types
- Compatibility
- Related
- Contribute
- License
What is this?
This is a small utility that helps you make new trees.
When should I use this?
You can use this utility to create a new tree by mapping all nodes with a given
function.
Creating new trees like this can lead to performance problems, as it creates
new objects for every node.
When dealing with potentially large trees, and relatively few changes, use
unist-util-visit
(or
unist-util-visit-parents
) instead.
To remove certain nodes, you can also walk the tree with unist-util-visit
, or
use unist-util-filter
(clones the tree instead of
mutating) or unist-util-remove
(mutates).
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-map
In Deno with esm.sh
:
import {map} from "https://esm.sh/unist-util-map@3"
In browsers with esm.sh
:
<script type="module">
import {map} from "https://esm.sh/unist-util-map@3?bundle"
</script>
Use
import {u} from 'unist-builder'
import {map} from 'unist-util-map'
const tree = u('tree', [
u('leaf', 'leaf 1'),
u('node', [u('leaf', 'leaf 2')]),
u('void'),
u('leaf', 'leaf 3')
])
const next = map(tree, (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:next
is a changed clone andtree
is not mutated.
API
This package exports the identifier map
.
There is no default export.
map(tree, mapFunction)
Create a new tree (Node
) by mapping all nodes with the given function
(MapFunction
).
Returns
New mapped tree (Node
).
function mapFunction(node, index, parent)
Function called with a node (Node
), its index (number?
), and its
parent (Node?
) to produce a new node.
Returns
Node to be used in the new tree (Node
).
The children on the returned node are not used.
if the original node has children, those are mapped instead.
Types
This package is fully typed with TypeScript.
It exports a type MapFunction<Tree extends Node = Node>
to properly type MapFunction
s.
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-filter
— create a new tree with all nodes that pass the given functionunist-util-flatmap
— create a new tree by expanding a node into manyunist-util-remove
— remove nodes from treesunist-util-select
— select nodes with CSS-like selectorsunist-util-visit
— walk treesunist-builder
— create 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, organization, or community you agree to abide by its terms.