| 1 | # unist-util-visit [](https://travis-ci.org/wooorm/unist-util-visit) [](https://codecov.io/github/wooorm/unist-util-visit?branch=master)
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| 2 |
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| 3 | [**Unist**](https://github.com/wooorm/unist) node visitor. Useful when working
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| 4 | with [**mdast**](https://github.com/wooorm/mdast) or
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| 5 | [**retext**](https://github.com/wooorm/retext).
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| 6 |
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| 7 | ## Installation
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| 8 |
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| 9 | [npm](https://docs.npmjs.com/cli/install):
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| 10 |
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| 11 | ```bash
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| 12 | npm install unist-util-visit
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| 13 | ```
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| 14 |
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| 15 | **unist-util-visit** is also available for [bower](http://bower.io/#install-packages),
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| 16 | [component](https://github.com/componentjs/component), and
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| 17 | [duo](http://duojs.org/#getting-started), and as an AMD, CommonJS, and globals
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| 18 | module, [uncompressed](unist-util-visit.js) and
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| 19 | [compressed](unist-util-visit.min.js).
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| 20 |
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| 21 | ## Usage
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| 22 |
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| 23 | ```js
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| 24 | var mdast = require('mdast');
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| 25 | var visit = require('unist-util-visit');
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| 26 |
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| 27 | mdast().use(function (ast) {
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| 28 | visit(ast, 'text', console.log.bind(console));
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| 29 | }).process('Some *emphasis*, **strongness**, and `code`.');
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| 30 | ```
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| 31 |
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| 32 | Yields:
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| 33 |
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| 34 | ```js
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| 35 | {'type': 'text', 'value': 'Some '}
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| 36 | {'type': 'text', 'value': 'emphasis'}
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| 37 | {'type': 'text', 'value': ', '}
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| 38 | {'type': 'text', 'value': 'strongness'}
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| 39 | {'type': 'text', 'value': ', and '}
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| 40 | {'type': 'text', 'value': '.'}
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| 41 | ```
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| 42 |
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| 43 | ## API
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| 44 |
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| 45 | ### visit([node](https://github.com/wooorm/unist#unist-nodes)\[, type\], callback\[, reverse\])
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| 46 |
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| 47 | > `visit` is synchronous.
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| 48 |
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| 49 | Visit nodes. Optionally by node type. Optionally in reverse.
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| 50 |
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| 51 | * `node` (`Node`)
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| 52 | — [**Unist** node](https://github.com/wooorm/unist#unist-nodes);
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| 53 |
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| 54 | * `type` (`string`, optional)
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| 55 | — Optional node type to invoke `callback` for. By default, all nodes are
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| 56 | visited.
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| 57 |
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| 58 | * `callback` (`function(node, index?, parent?)`)
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| 59 | — Callback invoked when a node (matching `type`?) is found. Invoked with
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| 60 | the node, its `index` in `parent` (or `null`), and its `parent` (or `null`).
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| 61 |
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| 62 | Can return `false` to immediately stop checking.
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| 63 |
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| 64 | * `reverse` (`boolean`, default: `false`, optional)
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| 65 | — When falsey, checking starts at the first child and continues through
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| 66 | to later children. When truthy, this is reversed.
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| 67 |
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| 68 | This **does not** mean checking starts at the deepest node and continues
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| 69 | on to the highest node.
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| 70 |
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| 71 | ## License
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| 72 |
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| 73 | [MIT](LICENSE) © [Titus Wormer](http://wooorm.com)
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