unist-util-parents
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!Chatchat-badgechatunist utility to add references to parents on nodes in a tree.
Contents
* [`parents(tree)`](#parentstree)
* [`Proxy`](#proxy)
What is this?
This utility creates a proxy of the tree that acts like the original tree upon reading, but each proxied node has a reference to its parent node.When should I use this?
This package can be very useful for problems where it is needed to figure out what a nodes ancestors are, because unist itself is a non-cyclical data structure, and thus does not provide that information. On the other hand, this info on ancestors can also be gathered when walking the tree withunist-util-visit-parents
unist-util-visit-parents.Install
This package is ESM onlyesm. In Node.js (version 16+), install with npm:npm install unist-util-parents
In Deno with
esm.sh
esmsh:import {parent} from 'https://esm.sh/unist-util-parents@3'
In browsers with
esm.sh
esmsh:<script type="module">
import {parent} from 'https://esm.sh/unist-util-parents@3?bundle'
</script>
Use
import {u} from 'unist-builder'
import {parents} from 'unist-util-parents'
const tree = u('root', [
u('leaf', 'leaf 1'),
u('node', [
u('leaf', 'leaf 2'),
u('void'),
u('node', [
u('leaf', 'leaf 3'),
u('node', [u('leaf', 'leaf 4')]),
u('void'),
u('leaf', 'leaf 5')
])
])
])
const wrapped = parents(tree)
// Leaf 4
const node = wrapped.children[1].children[2].children[1].children[0]
const chain = []
while (node) {
chain.push(node.type)
node = node.parent
}
console.log(chain.reverse())
Yields:
['root', 'node', 'node', 'node', 'leaf']
API
This package exports the identifierparents
api-parents.
There is no default export.parents(tree)
Create a proxy of tree
that acts like the original tree upon reading, but
each proxied node has a reference to its parent node.Notes
The returned proxy imposes two additional fields on all of its nodes:parent
— parent link (orundefined
for the root)node
— link to the original node
These new fields are not enumerable and the original tree is not changed. This means you can use
JSON.stringify
on the wrapped tree and it’s the same.wrapped.children
returns array of wrapped child nodes, so that any recursive
algorithm will work on a wrapped tree just as well.To write changes to the tree, use
.node
to access the original tree.Parameters
— tree to proxy
Returns
Proxy oftree
(Proxy
api-proxy).Proxy
A proxy of a Node
node that adds two additional fields:parent
— parent link (orundefined
for the root)node
— link to the original node
Types
This package is fully typed with TypeScript. It exports the additional typeProxy
api-proxy.Compatibility
Projects maintained by the unified collective are compatible with maintained versions of Node.js.When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line,
unist-util-parents@^3
,
compatible with Node.js 16.Related
— walk the tree with ancestral information
Contribute
Seecontributing.md
contributing in syntax-tree/.github
health for
ways to get started.
See support.md
support for ways to get help.This project has a code of conductcoc. By interacting with this repository, organisation, or community you agree to abide by its terms.