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# unist-util-is [![Build Status][travis-badge]][travis] [![Coverage Status][codecov-badge]][codecov]
[**Unist**][unist] utility to check if a node passes a test.
## Installation
[npm][]:
```bash
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(null, {children: []}); // false
is(null, node); // true
is('strong', node); // true
is('emphasis', node); // false
is(node, node) // true
is({type: 'paragraph'}, parent) // true
is({type: 'strong'}, parent) // false
is(test, node); // false
is(test, node, 4, parent); // false
is(test, node, 5, parent); // true
```
## API
### `is(test, node[, index, parent[, context]])`
###### Parameters
* `test` ([`Function`][test], `string`, `Object`, or `Array.<Test>`, optional)
— When not given, checks if `node` is a [`Node`][node].
When `string`, works like passing `function (node) {return
node.type === test}`.
When `array`, checks any one of the subtests pass.
When `object`, checks that all keys in `test` are in `node`,
and that they have (strictly) equal values
* `node` ([`Node`][node]) — Node to check. `false` is returned
* `index` (`number`, optional) — Position of `node` in `parent`
* `parent` (`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 non-empty `string`).
#### `function test(node[, index, parent])`
###### Parameters
* `node` (`Node`) — Node to test
* `index` (`number?`) — Position of `node` in `parent`
* `parent` (`Node?`) — Parent of `node`
###### Context
`*` — The to `is` given `context`.
###### Returns
`boolean?` — Whether `node` matches.
## 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
## License
[MIT][license] © [Titus Wormer][author]
<!-- Definitions -->
[travis-badge]: https://img.shields.io/travis/syntax-tree/unist-util-is.svg
[travis]: https://travis-ci.org/syntax-tree/unist-util-is
[codecov-badge]: https://img.shields.io/codecov/c/github/syntax-tree/unist-util-is.svg
[codecov]: https://codecov.io/github/syntax-tree/unist-util-is
[npm]: https://docs.npmjs.com/cli/install
[license]: LICENSE
[author]: http://wooorm.com
[unist]: https://github.com/syntax-tree/unist
[node]: https://github.com/syntax-tree/unist#node
[test]: #function-testnode-index-parent
|
