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https://github.com/syntax-tree/hast-util-is-element
utility to check if a node is a (certain) element
https://github.com/syntax-tree/hast-util-is-element
element hast hast-util html syntax-tree util
Last synced: about 2 months ago
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utility to check if a node is a (certain) element
- Host: GitHub
- URL: https://github.com/syntax-tree/hast-util-is-element
- Owner: syntax-tree
- License: mit
- Created: 2016-04-17T14:35:08.000Z (over 8 years ago)
- Default Branch: main
- Last Pushed: 2023-07-31T15:08:59.000Z (about 1 year ago)
- Last Synced: 2024-04-16T00:29:31.893Z (5 months ago)
- Topics: element, hast, hast-util, html, syntax-tree, util
- Language: JavaScript
- Homepage: https://unifiedjs.com
- Size: 146 KB
- Stars: 11
- Watchers: 8
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
- License: license
Awesome Lists containing this project
- awesome-syntax-tree - hast-util-is-element - Check if a node is a (certain) element. (hast utilities)
README
# hast-util-is-element
[![Build][build-badge]][build]
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[![Downloads][downloads-badge]][downloads]
[![Size][size-badge]][size]
[![Sponsors][sponsors-badge]][collective]
[![Backers][backers-badge]][collective]
[![Chat][chat-badge]][chat]
[hast][] utility to check if a node is a (certain) element.
## Contents
* [What is this?](#what-is-this)
* [When should I use this?](#when-should-i-use-this)
* [Install](#install)
* [Use](#use)
* [API](#api)
* [`isElement(element[, test[, index, parent[, context]]])`](#iselementelement-test-index-parent-context)
* [`convertElement(test)`](#convertelementtest)
* [`Check`](#check)
* [`Test`](#test)
* [`TestFunction`](#testfunction)
* [Types](#types)
* [Compatibility](#compatibility)
* [Security](#security)
* [Related](#related)
* [Contribute](#contribute)
* [License](#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
import {isElement} from 'https://esm.sh/hast-util-is-element@3?bundle'
```
## 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.
### `isElement(element[, test[, index, parent[, context]]])`
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.
### `convertElement(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 `element`, `index`, and `parent`.
###### Parameters
* `test` ([`Test`][api-test], optional)
— a test for a specific element
###### Returns
A check ([`Check`][api-check]).
### `Check`
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`).
### `Test`
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
```
### `TestFunction`
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`](https://github.com/syntax-tree/hast-util-has-property)
— check if a node has a property
* [`hast-util-is-body-ok-link`](https://github.com/rehypejs/rehype-minify/tree/main/packages/hast-util-is-body-ok-link)
— check if a node is “Body OK” link element
* [`hast-util-is-conditional-comment`](https://github.com/rehypejs/rehype-minify/tree/main/packages/hast-util-is-conditional-comment)
— check if a node is a conditional comment
* [`hast-util-is-css-link`](https://github.com/rehypejs/rehype-minify/tree/main/packages/hast-util-is-css-link)
— check if a node is a CSS link element
* [`hast-util-is-css-style`](https://github.com/rehypejs/rehype-minify/tree/main/packages/hast-util-is-css-style)
— check if a node is a CSS style element
* [`hast-util-embedded`](https://github.com/syntax-tree/hast-util-embedded)
— check if a node is an embedded element
* [`hast-util-heading`](https://github.com/syntax-tree/hast-util-heading)
— check if a node is a heading element
* [`hast-util-interactive`](https://github.com/syntax-tree/hast-util-interactive)
— check if a node is interactive
* [`hast-util-is-javascript`](https://github.com/rehypejs/rehype-minify/tree/main/packages/hast-util-is-javascript)
— check if a node is a JavaScript script element
* [`hast-util-labelable`](https://github.com/syntax-tree/hast-util-labelable)
— check whether a node is labelable
* [`hast-util-phrasing`](https://github.com/syntax-tree/hast-util-phrasing)
— check if a node is phrasing content
* [`hast-util-script-supporting`](https://github.com/syntax-tree/hast-util-script-supporting)
— check if a node is a script-supporting element
* [`hast-util-sectioning`](https://github.com/syntax-tree/hast-util-sectioning)
— check if a node is a sectioning element
* [`hast-util-transparent`](https://github.com/syntax-tree/hast-util-transparent)
— check if a node is a transparent element
* [`hast-util-whitespace`](https://github.com/syntax-tree/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
[build]: https://github.com/syntax-tree/hast-util-is-element/actions
[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/hast-util-is-element.svg
[coverage]: https://codecov.io/github/syntax-tree/hast-util-is-element
[downloads-badge]: https://img.shields.io/npm/dm/hast-util-is-element.svg
[downloads]: https://www.npmjs.com/package/hast-util-is-element
[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=hast-util-is-element
[size]: https://bundlejs.com/?q=hast-util-is-element
[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg
[backers-badge]: https://opencollective.com/unified/backers/badge.svg
[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