# unist-util-visit [![Build Status][build-badge]][build-page] [![Coverage Status][coverage-badge]][coverage-page]

[Unist][] node visitor.  Useful with working with [**remark**][remark],
[**retext**][retext], or [**rehype**][rehype].

## Installation

[npm][]:

```bash
npm install unist-util-visit
```

## Usage

```javascript
var remark = require('remark');
var visit = require('unist-util-visit');

remark().use(plugin).process('Some _emphasis_, **importance**, and `code`.');

function plugin() {
  return transformer;
  function transformer(tree) {
    visit(tree, 'text', visitor);
  }
  function visitor(node) {
    console.log(node);
  }
}
```

Yields:

```js
{type: 'text', value: 'Some '}
{type: 'text', value: 'emphasis'}
{type: 'text', value: ', '}
{type: 'text', value: 'strongness'}
{type: 'text', value: ', and '}
{type: 'text', value: '.'}
```

## API

### `visit(node[, type], visitor[, reverse])`

Visit nodes.  Optionally by node type.  Optionally in reverse.

###### Parameters

*   `node` ([`Node`][node])
    — Node to search;
*   `type` (`string`, optional)
    — Node type;
*   `visitor` ([Function][visitor])
    — Visitor invoked when a node is found;
*   `reverse` (`boolean`, default: `false`)
    — When falsey, checking starts at the first child and continues
    through to later children.  When truthy, this is reversed.
    This **does not** mean checking starts at the deepest node and
    continues on to the highest node.

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

Invoked when a node (when `type` is given, matching `type`) is found.

###### Parameters

*   `node` (`Node`) — Found node;
*   `index` (`number?`) — Position of `node` in `parent`;
*   `index` (`Node?`) — Parent of `node`.

###### Returns

`boolean?` - When `false`, visiting is immediately stopped.

## License

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

<!-- Definition -->

[build-badge]: https://img.shields.io/travis/wooorm/unist-util-visit.svg

[build-page]: https://travis-ci.org/wooorm/unist-util-visit

[coverage-badge]: https://img.shields.io/codecov/c/github/wooorm/unist-util-visit.svg

[coverage-page]: https://codecov.io/github/wooorm/unist-util-visit?branch=master

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

[license]: LICENSE

[author]: http://wooorm.com

[unist]: https://github.com/wooorm/unist

[retext]: https://github.com/wooorm/retext

[remark]: https://github.com/wooorm/remark

[rehype]: https://github.com/wooorm/rehype

[node]: https://github.com/wooorm/unist#node

[visitor]: #stop--visitornode-index-parent