unist-util-is

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[unist][] utility to check if nodes pass a test.

* What is this?
* When should I use this?
* Install
* Use
* API
* [is(node[, test[, index, parent[, context]]])](#isnode-test-index-parent-context)
* convert(test)
* Check
* Test
* TestFunction
* Examples
* Example of convert
* 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][hast-util-is-element], works on hast
elements.

For more advanced tests, [unist-util-select][unist-util-select] can be used
to match against CSS selectors.

Install

This package is [ESM only][esm].
In Node.js (version 16+), install with [npm][]:

``sh npm install unist-util-is`

In Deno with [esm.sh][esmsh]:

`js import {is} from 'https://esm.sh/unist-util-is@6'`

In browsers with [esm.sh][esmsh]:

`html`

`Use`

`js 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][api-convert] and [is][api-is]. There is no default export.

`$3`

Check if node is a Node and whether it passes the given test.

###### Parameters

* node (unknown, optional) — thing to check, typically [Node][node] *test ([Test][api-test], optional) — a test for a specific element *index (number, optional) — the node’s position in its parent *parent ([Node][node], optional) — the node’s parent *context (unknown, optional) — context object (this) to call test with

###### Returns

Whether node is a [Node][node] and passes a test (boolean).

###### Throws

When an incorrect test, index, or parentis given. There is no error thrown whennode is not a node.

`$3`

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: anode, index, and parent.

###### Parameters

* test ([Test][api-test], optional) — a test for a specific node

###### Returns

A check ([Check][api-check]).

`$3`

Check that an arbitrary value is a node (TypeScript type).

###### Parameters

* this (unknown, optional) — context object (this) to call testwith *node (unknown) — anything (typically a node) *index (number, optional) — the node’s position in its parent *parent ([Node][node], optional) — the node’s parent

###### Returns

Whether this is a node and passes a test (boolean).

`$3`

Check for an arbitrary node (TypeScript type).

###### Type

Checks that the given thing is a node, and then:

* when string, checks that the node has that tag name * whenfunction, see [TestFunction][api-test-function] * whenobject, checks that all keys in test are in node, and that they have (strictly) equal values * whenArray, checks if one of the subtests pass

`$3`

Check if a node passes a test (TypeScript type).

###### Parameters

* node ([Node][node]) — a node *index (number or undefined) — the node’s position in its parent *parent ([Node][node] or undefined) — the node’s parent

###### Returns

Whether this node passes the test (boolean, optional).

`Examples`

`$3`

`js 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:

`js [{type: 'leaf', value: '2'}, {type: 'leaf', value: '5'}]`

`Types`

This package is fully typed with [TypeScript][]. It exports the additional types [Check][api-check], [Test][api-test], [TestFunction][api-test-function].

`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][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 conduct][coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.

License

[MIT][license] © [Titus Wormer][author]

[api-check]: #check

[api-convert]: #converttest

[api-is]: #isnode-test-index-parent-context

[api-test]: #test

[api-test-function]: #testfunction

[author]: https://wooorm.com

[backers-badge]: https://opencollective.com/unified/backers/badge.svg

[build]: https://github.com/syntax-tree/unist-util-is/actions

[build-badge]: https://github.com/syntax-tree/unist-util-is/workflows/main/badge.svg

[chat]: https://github.com/syntax-tree/unist/discussions

[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg

[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md

[collective]: https://opencollective.com/unified

[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md

[coverage]: https://codecov.io/github/syntax-tree/unist-util-is

[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/unist-util-is.svg

[downloads]: https://www.npmjs.com/package/unist-util-is

[downloads-badge]: https://img.shields.io/npm/dm/unist-util-is.svg

[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[esmsh]: https://esm.sh

[hast-util-is-element]: https://github.com/syntax-tree/hast-util-is-element

[health]: https://github.com/syntax-tree/.github

[license]: license

[node]: https://github.com/syntax-tree/unist#node

[npm]: https://docs.npmjs.com/cli/install

[size]: https://bundlejs.com/?q=unist-util-is

[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=unist-util-is

[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg

[support]: https://github.com/syntax-tree/.github/blob/main/support.md

[typescript]: https://www.typescriptlang.org

[unist]: https://github.com/syntax-tree/unist

[unist-util-select]: https://github.com/syntax-tree/unist-util-select

unist-util-is

[unist][] utility to check if nodes pass a test.

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][hast-util-is-element], works on hast
elements.

For more advanced tests, [unist-util-select][unist-util-select] can be used
to match against CSS selectors.

Install

This package is [ESM only][esm].
In Node.js (version 16+), install with [npm][]:

``sh npm install unist-util-is`

In Deno with [esm.sh][esmsh]:

`js import {is} from 'https://esm.sh/unist-util-is@6'`

In browsers with [esm.sh][esmsh]:

`html`

`Use`

`js 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][api-convert] and [is][api-is]. There is no default export.

`$3`

Check if node is a Node and whether it passes the given test.

###### Parameters

###### Returns

Whether node is a [Node][node] and passes a test (boolean).

###### Throws

When an incorrect test, index, or parentis given. There is no error thrown whennode is not a node.

`$3`

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: anode, index, and parent.

###### Parameters

* test ([Test][api-test], optional) — a test for a specific node

###### Returns

A check ([Check][api-check]).

`$3`

Check that an arbitrary value is a node (TypeScript type).

###### Parameters

###### Returns

Whether this is a node and passes a test (boolean).

`$3`

Check for an arbitrary node (TypeScript type).

###### Type

Checks that the given thing is a node, and then:

`$3`

Check if a node passes a test (TypeScript type).

###### Parameters

* node ([Node][node]) — a node *index (number or undefined) — the node’s position in its parent *parent ([Node][node] or undefined) — the node’s parent

###### Returns

Whether this node passes the test (boolean, optional).

`Examples`

`$3`

`js 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:

`js [{type: 'leaf', value: '2'}, {type: 'leaf', value: '5'}]`

`Types`

This package is fully typed with [TypeScript][]. It exports the additional types [Check][api-check], [Test][api-test], [TestFunction][api-test-function].

`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`

`Contribute`

See [contributing.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 conduct][coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.

License

[api-check]: #check

[api-convert]: #converttest

[api-is]: #isnode-test-index-parent-context

[api-test]: #test

[api-test-function]: #testfunction

[author]: https://wooorm.com

[backers-badge]: https://opencollective.com/unified/backers/badge.svg

[build]: https://github.com/syntax-tree/unist-util-is/actions

[build-badge]: https://github.com/syntax-tree/unist-util-is/workflows/main/badge.svg

[chat]: https://github.com/syntax-tree/unist/discussions

[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg

[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md

[collective]: https://opencollective.com/unified

[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md

[coverage]: https://codecov.io/github/syntax-tree/unist-util-is

[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/unist-util-is.svg

[downloads]: https://www.npmjs.com/package/unist-util-is

[downloads-badge]: https://img.shields.io/npm/dm/unist-util-is.svg

[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[esmsh]: https://esm.sh

[hast-util-is-element]: https://github.com/syntax-tree/hast-util-is-element

[health]: https://github.com/syntax-tree/.github

[license]: license

[node]: https://github.com/syntax-tree/unist#node

[npm]: https://docs.npmjs.com/cli/install

[size]: https://bundlejs.com/?q=unist-util-is

[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=unist-util-is

[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg

[support]: https://github.com/syntax-tree/.github/blob/main/support.md

[typescript]: https://www.typescriptlang.org

[unist]: https://github.com/syntax-tree/unist

[unist-util-select]: https://github.com/syntax-tree/unist-util-select

unist-util-is

unist-util-is

Contents

What is this?

When should I use this?

Install

`Use`

`API`

`$3`

`$3`

`$3`

`$3`

`$3`

`Examples`

`$3`

`Types`

`Compatibility`

`Related`

`Contribute`

License

unist-util-is

unist-util-is

Contents

What is this?

When should I use this?

Install

`Use`

`API`

`$3`

`$3`

`$3`

`$3`

`$3`

`Examples`

`$3`

`Types`

`Compatibility`

`Related`

`Contribute`

License