hast-util-is-element

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[hast][] utility to check if a node is a (certain) element.

Contents

* What is this?
* When should I use this?
* Install
* Use
* API
* [isElement(element[, test[, index, parent[, context]]])](#iselementelement-test-index-parent-context)
* convertElement(test)
* Check
* Test
* TestFunction
* Types
* Compatibility
* Security
* Related
* Contribute
* License

What is this?

This package is a small utility that checks that a node is a certain element.

When should I use this?

Use this small utility if you find yourself repeating code for checking what
elements nodes are.

A similar package, [unist-util-is][unist-util-is], works on any unist node.

For more advanced tests, [hast-util-select][hast-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 hast-util-is-element
`

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

`js
import {isElement} from 'https://esm.sh/hast-util-is-element@3'
`

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

`html

`

Use

`js
import {isElement} from 'hast-util-is-element'

isElement({type: 'text', value: 'foo'}) // => false
isElement({type: 'element', tagName: 'a', properties: {}, children: []}) // => true
isElement({type: 'element', tagName: 'a', properties: {}, children: []}, 'a') // => true
isElement({type: 'element', tagName: 'a', properties: {}, children: []}, 'b') // => false
isElement({type: 'element', tagName: 'a', properties: {}, children: []}, ['a', 'area']) // => true
`

API

This package exports the identifiers
[convertElement][api-convert-element] and
[isElement][api-is-element].
There is no default export.

$3

Check if element is an Element and whether it passes the given test.

###### Parameters

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

###### Returns

Whether element is an Element and passes a test (boolean).

###### Throws

When an incorrect test, index, or parent is given.
There is no error thrown when element is not a node or not an element.

$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:
a element, index, and parent.

###### Parameters

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

###### Returns

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

$3

Check that an arbitrary value is an element (TypeScript type).

###### Parameters

* this (unknown, optional)
— context object (this) to call test with
* element (unknown)
— anything (typically an element)
* index (number, optional)
— position of element in its parent
* parent ([Parent][hast-parent], optional)
— parent of element

###### Returns

Whether this is an element and passes a test (boolean).

$3

Check for an arbitrary element (TypeScript type).

* when string, checks that the element has that tag name
* when function, see [TestFunction][api-test-function]
* when Array, checks if one of the subtests pass

###### Type

`ts
type Test =
| Array
| TestFunction
| string
| null
| undefined
`

$3

Check if an element passes a test (TypeScript type).

###### Parameters

* element ([Element][hast-element])
— an element
* index (number or undefined)
— position of element in its parent
* parent ([Parent][hast-parent] or undefined)
— parent of element

###### Returns

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

Types

This package is fully typed with [TypeScript][].
It exports the additional types [Check][api-check],
[Test][api-test], and
[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, hast-util-is-element@^3,
compatible with Node.js 16.

Security

hast-util-is-element does not change the syntax tree so there are no openings
for [cross-site scripting (XSS)][xss] attacks.

Related

* hast-util-has-property
— check if a node has a property
* hast-util-is-body-ok-link
— check if a node is “Body OK” link element
* hast-util-is-conditional-comment
— check if a node is a conditional comment
* hast-util-is-css-link
— check if a node is a CSS link element
* hast-util-is-css-style
— check if a node is a CSS style element
* hast-util-embedded
— check if a node is an embedded element
* hast-util-heading
— check if a node is a heading element
* hast-util-interactive
— check if a node is interactive
* hast-util-is-javascript
— check if a node is a JavaScript script element
* hast-util-labelable
— check whether a node is labelable
* hast-util-phrasing
— check if a node is phrasing content
* hast-util-script-supporting
— check if a node is a script-supporting element
* hast-util-sectioning
— check if a node is a sectioning element
* hast-util-transparent
— check if a node is a transparent element
* hast-util-whitespace
— check if a node is inter-element whitespace

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]

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

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

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

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

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

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

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

[esmsh]: https://esm.sh

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

[license]: license

[author]: https://wooorm.com

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

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

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

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

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

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

[hast-parent]: https://github.com/syntax-tree/hast#parent

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

[xss]: https://en.wikipedia.org/wiki/Cross-site_scripting

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

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

[api-is-element]: #iselementelement-test-index-parent-context

[api-convert-element]: #convertelementtest

[api-check]: #check

[api-test]: #test

[api-test-function]: #testfunction