# unist-util-visit

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[**unist**][unist] utility to visit nodes.

## Install

This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c):
Node 12+ is needed to use it and it must be `import`ed instead of `require`d.

[npm][]:

```sh
npm install unist-util-visit
```

## Use

```js
import {u} from 'unist-builder'
import {visit} from 'unist-util-visit'

const tree = u('tree', [
  u('leaf', '1'),
  u('node', [u('leaf', '2')]),
  u('void'),
  u('leaf', '3')
])

visit(tree, 'leaf', (node) => {
  console.log(node)
})
```

Yields:

```js
{ type: 'leaf', value: '1' }
{ type: 'leaf', value: '2' }
{ type: 'leaf', value: '3' }
```

Note: this example also uses `unist-builder`, to run the example ensure both `unist-builder` and `unist-util-visit` are installed:

```sh
npm install unist-builder unist-util-visit
```

## API

This package exports the following identifiers: `visit`, `CONTINUE`, `SKIP`, and
`EXIT`.
There is no default export.

### `visit(tree[, test], visitor[, reverse])`

This function works exactly the same as [`unist-util-visit-parents`][vp],
but `visitor` has a different signature.

#### `next? = visitor(node, index, parent)`

Instead of being passed an array of ancestors, `visitor` is called with the
`node`’s [`index`][index] and its [`parent`][parent].  The optional return value
`next` is documented in [`unist-util-visit-parents`][vp]’s readme.

Otherwise the same as [`unist-util-visit-parents`][vp].

## Related

*   [`unist-util-visit-parents`][vp]
    — Like `visit`, but with a stack of parents
*   [`unist-util-filter`](https://github.com/syntax-tree/unist-util-filter)
    — Create a new tree with all nodes that pass a test
*   [`unist-util-map`](https://github.com/syntax-tree/unist-util-map)
    — Create a new tree with all nodes mapped by a given function
*   [`unist-util-flatmap`](https://gitlab.com/staltz/unist-util-flatmap)
    — Create a new tree by mapping (to an array) with the given function
*   [`unist-util-remove`](https://github.com/syntax-tree/unist-util-remove)
    — Remove nodes from a tree that pass a test
*   [`unist-util-select`](https://github.com/syntax-tree/unist-util-select)
    — Select nodes with CSS-like selectors

## 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, organization, or community you agree to
abide by its terms.

## License

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

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[license]: license

[author]: https://wooorm.com

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

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

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

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

[vp]: https://github.com/syntax-tree/unist-util-visit-parents

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

[parent]: https://github.com/syntax-tree/unist#parent-1