GitHub - syntax-tree/unist-util-is: utility to check if a node passes a test (original) (raw)
unist-util-is
unist utility to check if nodes pass a test.
Contents
- What is this?
- When should I use this?
- Install
- Use
- API
- Examples
- Types
- Compatibility
- Related
- Contribute
- License
What is this?
This package is a small utility that checks that a node is a certain node.
When should I use this?
Use this small utility if you find yourself repeating code for checking what nodes are.
A similar package, hast-util-is-element, works on hast elements.
For more advanced tests, unist-util-select can be used to match against CSS selectors.
Install
This package is ESM only. In Node.js (version 16+), install with npm:
npm install unist-util-is
In Deno with esm.sh:
import {is} from 'https://esm.sh/unist-util-is@6'
In browsers with esm.sh:
Use
import {is} from 'unist-util-is'
const node = {type: 'strong'} const parent = {type: 'paragraph', children: [node]}
is() // => false is({children: []}) // => false is(node) // => true is(node, 'strong') // => true is(node, 'emphasis') // => false
is(node, node) // => true is(parent, {type: 'paragraph'}) // => true is(parent, {type: 'strong'}) // => false
is(node, test) // => false is(node, test, 4, parent) // => false is(node, test, 5, parent) // => true
function test(node, n) { return n === 5 }
API
This package exports the identifiers convert andis. There is no default export.
is(node[, test[, index, parent[, context]]])
Check if node
is a Node
and whether it passes the given test.
Parameters
node
(unknown
, optional) — thing to check, typically Nodetest
(Test, optional) — a test for a specific elementindex
(number
, optional) — the node’s position in its parentparent
(Node, optional) — the node’s parentcontext
(unknown
, optional) — context object (this
) to calltest
with
Returns
Whether node
is a Node and passes a test (boolean
).
Throws
When an incorrect test
, index
, or parent
is given. There is no error thrown when node
is not a node.
convert(test)
Generate a check from a test.
Useful if you’re going to test many nodes, for example when creating a utility where something else passes a compatible test.
The created function is a bit faster because it expects valid input only: a node
, index
, and parent
.
Parameters
test
(Test, optional) — a test for a specific node
Returns
A check (Check).
Check
Check that an arbitrary value is a node (TypeScript type).
Parameters
this
(unknown
, optional) — context object (this
) to calltest
withnode
(unknown
) — anything (typically a node)index
(number
, optional) — the node’s position in its parentparent
(Node, optional) — the node’s parent
Returns
Whether this is a node and passes a test (boolean
).
Test
Check for an arbitrary node (TypeScript type).
Type
type Test = | Array<Record<string, unknown> | TestFunction | string> | Record<string, unknown> | TestFunction | string | null | undefined
Checks that the given thing is a node, and then:
- when
string
, checks that the node has that tag name - when
function
, see TestFunction - when
object
, checks that all keys in test are in node, and that they have (strictly) equal values - when
Array
, checks if one of the subtests pass
TestFunction
Check if a node passes a test (TypeScript type).
Parameters
node
(Node) — a nodeindex
(number
orundefined
) — the node’s position in its parentparent
(Node orundefined
) — the node’s parent
Returns
Whether this node passes the test (boolean
, optional).
Examples
Example of convert
import {u} from 'unist-builder' import {convert} from 'unist-util-is'
const test = convert('leaf')
const tree = u('tree', [ u('node', [u('leaf', '1')]), u('leaf', '2'), u('node', [u('leaf', '3'), u('leaf', '4')]), u('leaf', '5') ])
const leafs = tree.children.filter(function (child, index) { return test(child, index, tree) })
console.log(leafs)
Yields:
[{type: 'leaf', value: '2'}, {type: 'leaf', value: '5'}]
Types
This package is fully typed with TypeScript. It exports the additional types Check,Test,TestFunction.
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-is@^6
, compatible with Node.js 16.
Related
- unist-util-find-after— find a node after another node
- unist-util-find-before— find a node before another node
- unist-util-find-all-after— find all nodes after another node
- unist-util-find-all-before— find all nodes before another node
- unist-util-find-all-between— find all nodes between two nodes
- unist-util-filter— create a new tree with nodes that pass a check
- unist-util-remove— remove nodes from tree
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.