# hast-util-is-element

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

## Install

[npm][]:

```sh
npm install hast-util-is-element
```

## Usage

```js
var is = require('hast-util-is-element')

is({type: 'text', value: 'foo'}) // => false

is({type: 'element', tagName: 'a'}, 'a') // => true

is({type: 'element', tagName: 'a'}, ['a', 'area']) // => true
```

## API

### `isElement(node[, tagName|tagNames])`

Check if the given value is a (certain) [*element*][element].

*   When given a `tagName` or `tagNames`, checks that `node` is an
    [*element*][element] whose `tagName` field matches `tagName` or is included
    in `tagNames`
*   Otherwise checks that `node` is an [*element*][element]

###### Parameters

*   `node` (`*`) — Value to check, probably [`Node`][node]
*   `tagName` (`string`, optional) — Value that `node`s `tagName` field should
    match
*   `tagNames` (`Array.<string>`, optional) — Values that should include `node`s
    `tagName` field should match

###### Returns

`boolean` — whether `node` passes the test.

###### Throws

`Error` — When the second parameter is given but invalid.

## Contribute

See [`contributing.md` in `syntax-tree/.github`][contributing] 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, organisation, or community you agree to
abide by its terms.

## License

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

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[chat]: https://spectrum.chat/unified/syntax-tree

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

[license]: license

[author]: https://wooorm.com

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

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

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

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

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

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