--- /dev/null
+# unist-util-is
+
+[![Build][build-badge]][build]
+[![Coverage][coverage-badge]][coverage]
+[![Downloads][downloads-badge]][downloads]
+[![Size][size-badge]][size]
+[![Sponsors][sponsors-badge]][collective]
+[![Backers][backers-badge]][collective]
+[![Chat][chat-badge]][chat]
+
+[**unist**][unist] utility to check if a node passes a test.
+
+## Install
+
+[npm][]:
+
+```sh
+npm install unist-util-is
+```
+
+## Usage
+
+```js
+var is = require('unist-util-is')
+
+var node = {type: 'strong'}
+var parent = {type: 'paragraph', children: [node]}
+
+function test(node, n) {
+ return n === 5
+}
+
+is() // => false
+is({children: []}) // => false
+is(node) // => true
+is(node, 'strong') // => true
+is(node, 'emphasis') // => false
+
+is(node, node) // => true
+is(parent, {type: 'paragraph'}) // => true
+is(parent, {type: 'strong'}) // => false
+
+is(node, test) // => false
+is(node, test, 4, parent) // => false
+is(node, test, 5, parent) // => true
+```
+
+## API
+
+### `is(node[, test[, index, parent[, context]]])`
+
+###### Parameters
+
+* `node` ([`Node`][node]) — Node to check.
+* `test` ([`Function`][test], `string`, `Object`, or `Array.<Test>`, optional)
+ — When not given, checks if `node` is a [`Node`][node].
+ When `string`, works like passing `node => node.type === test`.
+ When `array`, checks if any one of the subtests pass.
+ When `object`, checks that all keys in `test` are in `node`,
+ and that they have strictly equal values
+* `index` (`number`, optional) — [Index][] of `node` in `parent`
+* `parent` ([`Node`][node], optional) — [Parent][] of `node`
+* `context` (`*`, optional) — Context object to invoke `test` with
+
+###### Returns
+
+`boolean` — Whether `test` passed *and* `node` is a [`Node`][node] (object with
+`type` set to a non-empty `string`).
+
+#### `function test(node[, index, parent])`
+
+###### Parameters
+
+* `node` ([`Node`][node]) — Node to check
+* `index` (`number?`) — [Index][] of `node` in `parent`
+* `parent` ([`Node?`][node]) — [Parent][] of `node`
+
+###### Context
+
+`*` — The to `is` given `context`.
+
+###### Returns
+
+`boolean?` — Whether `node` matches.
+
+### `is.convert(test)`
+
+Create a test function from `test`, that can later be called with a `node`,
+`index`, and `parent`.
+Useful if you’re going to test many nodes, for example when creating a utility
+where something else passes an is-compatible test.
+
+Can also be accessed with `require('unist-util-is/convert')`.
+
+For example:
+
+```js
+var u = require('unist-builder')
+var convert = require('unist-util-is/convert')
+
+var test = convert('leaf')
+
+var tree = u('tree', [
+ u('node', [u('leaf', '1')]),
+ u('leaf', '2'),
+ u('node', [u('leaf', '3'), u('leaf', '4')]),
+ u('leaf', '5')
+])
+
+var leafs = tree.children.filter((child, index) => test(child, index, tree))
+
+console.log(leafs)
+```
+
+Yields:
+
+```js
+[({type: 'leaf', value: '2'}, {type: 'leaf', value: '5'})]
+```
+
+## Related
+
+* [`unist-util-find-after`](https://github.com/syntax-tree/unist-util-find-after)
+ — Find a node after another node
+* [`unist-util-find-before`](https://github.com/syntax-tree/unist-util-find-before)
+ — Find a node before another node
+* [`unist-util-find-all-after`](https://github.com/syntax-tree/unist-util-find-all-after)
+ — Find all nodes after another node
+* [`unist-util-find-all-before`](https://github.com/syntax-tree/unist-util-find-all-before)
+ — Find all nodes before another node
+* [`unist-util-find-all-between`](https://github.com/mrzmmr/unist-util-find-all-between)
+ — Find all nodes between two nodes
+* [`unist-util-find`](https://github.com/blahah/unist-util-find)
+ — Find nodes matching a predicate
+* [`unist-util-filter`](https://github.com/eush77/unist-util-filter)
+ — Create a new tree with nodes that pass a check
+* [`unist-util-remove`](https://github.com/eush77/unist-util-remove)
+ — Remove nodes from tree
+
+## 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]
+
+<!-- Definitions -->
+
+[build-badge]: https://img.shields.io/travis/syntax-tree/unist-util-is.svg
+
+[build]: https://travis-ci.org/syntax-tree/unist-util-is
+
+[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/unist-util-is.svg
+
+[coverage]: https://codecov.io/github/syntax-tree/unist-util-is
+
+[downloads-badge]: https://img.shields.io/npm/dm/unist-util-is.svg
+
+[downloads]: https://www.npmjs.com/package/unist-util-is
+
+[size-badge]: https://img.shields.io/bundlephobia/minzip/unist-util-is.svg
+
+[size]: https://bundlephobia.com/result?p=unist-util-is
+
+[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/join%20the%20community-on%20spectrum-7b16ff.svg
+
+[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
+
+[unist]: https://github.com/syntax-tree/unist
+
+[node]: https://github.com/syntax-tree/unist#node
+
+[parent]: https://github.com/syntax-tree/unist#parent-1
+
+[index]: https://github.com/syntax-tree/unist#index
+
+[test]: #function-testnode-index-parent
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