unist-util-is
unist utility to check if a node passes a test.
Install
This package is ESM only:
Node 12+ is needed to use it and it must be import
ed instead of require
d.
npm:
npm install unist-util-is
Use
import {is} from 'unist-util-is'
const node = {type: 'strong'}
const parent = {type: 'paragraph', children: [node]}
function test(node, n) {
return n === 5
}
is()
is({children: []})
is(node)
is(node, 'strong')
is(node, 'emphasis')
is(node, node)
is(parent, {type: 'paragraph'})
is(parent, {type: 'strong'})
is(node, test)
is(node, test, 4, parent)
is(node, test, 5, parent)
API
This package exports the following identifiers: is
, convert
.
There is no default export.
is(node[, test[, index, parent[, context]]])
Parameters
node
(Node
) — Node to check.test
(Function
, string
, Object
, or Array.<Test>
, optional)
— When nullish, checks if node
is a Node
.
When string
, works like passing node => node.type === test
.
When array
, checks if any one of the subtests pass.
When object
, checks that all keys in test
are in node
,
and that they have strictly equal valuesindex
(number
, optional) — Index of node
in parent
parent
(Node
, optional) — Parent of node
context
(*
, optional) — Context object to invoke test
with
Returns
boolean
— Whether test
passed and node
is a Node
(object with
type
set to a non-empty string
).
function test(node[, index, parent])
Parameters
Context
*
— The to is
given context
.
Returns
boolean?
— Whether node
matches.
convert(test)
Create a test function from test
, that can later be called with a node
,
index
, and parent
.
Useful if you’re going to test many nodes, for example when creating a utility
where something else passes an is-compatible test.
The created function is slightly faster because it expects valid input only.
Therefore, passing invalid input, yields unexpected results.
For example:
import u from 'unist-builder'
import {convert} from 'unist-util-is'
var test = convert('leaf')
var tree = u('tree', [
u('node', [u('leaf', '1')]),
u('leaf', '2'),
u('node', [u('leaf', '3'), u('leaf', '4')]),
u('leaf', '5')
])
var leafs = tree.children.filter((child, index) => test(child, index, tree))
console.log(leafs)
Yields:
[{type: 'leaf', value: '2'}, {type: 'leaf', value: '5'}]
Related
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 © Titus Wormer