# mdast-util-assert

> mdast utility to assert trees

Latest version **5.0.0** (published 2023-07-08) · MIT license · 0 weekly downloads

## Install

```sh
npm install mdast-util-assert
pnpm add mdast-util-assert
yarn add mdast-util-assert
bun add mdast-util-assert
```

## Health

**Score 30/100 (F)** — status: abandoned.

Positive: has types; esm support; no vulnerabilities; high quality score.

Warnings: low downloads.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 5.0.0 |
| Published | 2023-07-08 |
| First published | 2016-07-18 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM |
| Dependencies | 5 |
| Unpacked size | 27.3 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| Author | Titus Wormer |
| Maintainers | wooorm, kmck |
| Keywords | unist, mdast, mdast-util, util, utility, assert, check, test |

## Links

- npm: https://www.npmjs.com/package/mdast-util-assert
- Repository: https://github.com/syntax-tree/mdast-util-assert
- Homepage: https://github.com/syntax-tree/mdast-util-assert#readme
- Issues: https://github.com/syntax-tree/mdast-util-assert/issues
- Funding: https://opencollective.com/unified
- npm.io page: https://npm.io/package/mdast-util-assert

## Dependencies (5)

- [mapz](https://npm.io/package/mapz.md) ^2.0.0
- [zwitch](https://npm.io/package/zwitch.md) ^2.0.0
- [@types/mdast](https://npm.io/package/@types/mdast.md) ^4.0.0
- [@types/unist](https://npm.io/package/@types/unist.md) ^3.0.0
- [unist-util-assert](https://npm.io/package/unist-util-assert.md) ^4.0.0

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## Recent versions

- 5.0.0 (latest) — 2023-07-08
- 4.0.1 — 2023-01-26
- 4.0.0 — 2021-05-10
- 3.0.0 — 2020-02-22
- 2.0.1 — 2019-05-24
- 2.0.0 — 2018-11-11
- 1.0.2 — 2018-08-20
- 1.0.1 — 2017-06-13
- 1.0.0 — 2016-07-18

## README

# mdast-util-assert

[![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]

[mdast][] utility to assert trees.

## Contents

*   [What is this?](#what-is-this)
*   [When should I use this?](#when-should-i-use-this)
*   [Install](#install)
*   [Use](#use)
*   [API](#api)
    *   [`assert(tree[, parent])`](#asserttree-parent)
    *   [`parent(tree[, parent])`](#parenttree-parent)
    *   [`literal(node[, parent])`](#literalnode-parent)
    *   [`_void(node[, parent])`](#_voidnode-parent)
    *   [`wrap(fn)`](#wrapfn)
    *   [`AssertionError`](#assertionerror)
*   [Types](#types)
*   [Compatibility](#compatibility)
*   [Security](#security)
*   [Related](#related)
*   [Contribute](#contribute)
*   [License](#license)

## What is this?

This package is a tiny utility that helps you deal with nodes.

## When should I use this?

This utility is typically useful when you expect certain nodes in your APIs
and want to make sure they’re valid and as expected.

A different utility, [`unist-util-assert`][unist-util-assert], does the same but
for any [unist][] node.

## Install

This package is [ESM only][esm].
In Node.js (version 16+), install with [npm][]:

```sh
npm install mdast-util-assert
```

In Deno with [`esm.sh`][esmsh]:

```js
import {assert} from 'https://esm.sh/mdast-util-assert@5'
```

In browsers with [`esm.sh`][esmsh]:

```html
<script type="module">
  import {assert} from 'https://esm.sh/mdast-util-assert@5?bundle'
</script>
```

## Use

```js
import {assert} from 'mdast-util-assert'

assert({type: 'root', children: []})
assert({type: 'break'})
assert({type: 'listItem', checked: true, children: []})
// All OK.

assert({children: []})
// AssertionError: node should have a type: `{ children: [] }`

assert({type: 'paragraph', value: 'foo'})
// AssertionError: parent should have children: `{ type: 'paragraph', value: 'foo' }`
```

## API

This package exports the identifiers [`_void`][api-void],
[`assert`][api-assert], [`literal`][api-literal], [`parent`][api-parent],
and [`wrap`][api-wrap].
There is no default export.

### `assert(tree[, parent])`

Assert that `tree` is a valid mdast [`Node`][node].

If `tree` is a parent, all children will be asserted too.

Supports unknown mdast nodes.

###### Parameters

*   `tree` (`unknown`)
    — thing to assert
*   `parent` ([`Parent`][parent], optional)
    — optional, valid parent

###### Returns

Nothing.

###### Throws

When `tree` (or its descendants) is not an mdast node
([`AssertionError`][api-assertion-error]).

### `parent(tree[, parent])`

Assert that `tree` is a valid mdast [`Parent`][parent].

All children will be asserted too.

Supports unknown mdast nodes.

###### Parameters

*   `tree` (`unknown`)
    — thing to assert
*   `parent` ([`Parent`][parent], optional)
    — optional, valid parent

###### Returns

Nothing.

###### Throws

When `tree` is not a parent or its descendants are not nodes
([`AssertionError`][api-assertion-error])

### `literal(node[, parent])`

Assert that `node` is a valid mdast [`Literal`][literal].

Supports unknown mdast nodes.

###### Parameters

*   `node` (`unknown`)
    — thing to assert
*   `parent` ([`Parent`][parent], optional)
    — optional, valid parent

###### Returns

Nothing.

###### Throws

When `node` is not an mdast literal ([`AssertionError`][api-assertion-error]).

### `_void(node[, parent])`

Re-exported from [`unist-util-assert`][unist-util-assert-void].

### `wrap(fn)`

Re-exported from [`unist-util-assert`][unist-util-assert-wrap].

### `AssertionError`

Re-exported from [`unist-util-assert`][unist-util-assert-assertionerror].

## Types

This package is fully typed with [TypeScript][].
It exports the additional type [`AssertionError`][api-assertion-error].

## Compatibility

Projects maintained by the unified collective are compatible with maintained
versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of
Node.
This means we try to keep the current release line, `mdast-util-assert@^5`,
compatible with Node.js 16.

## Security

Use of `mdast-util-assert` does not involve **[hast][]** so there are no
openings for [cross-site scripting (XSS)][xss] attacks.

## Related

*   [`unist-util-assert`][unist-util-assert]
    — check unist nodes
*   [`hast-util-assert`](https://github.com/syntax-tree/hast-util-assert)
    — check hast nodes
*   [`nlcst-test`](https://github.com/syntax-tree/nlcst-test)
    — check nlcst nodes

## Contribute

See [`contributing.md`][contributing] in [`syntax-tree/.github`][health] 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]

<!-- Definitions -->

[build-badge]: https://github.com/syntax-tree/mdast-util-assert/workflows/main/badge.svg

[build]: https://github.com/syntax-tree/mdast-util-assert/actions

[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/mdast-util-assert.svg

[coverage]: https://codecov.io/github/syntax-tree/mdast-util-assert

[downloads-badge]: https://img.shields.io/npm/dm/mdast-util-assert.svg

[downloads]: https://www.npmjs.com/package/mdast-util-assert

[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=mdast-util-assert

[size]: https://bundlejs.com/?q=mdast-util-assert

[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/chat-discussions-success.svg

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

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

[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[esmsh]: https://esm.sh

[typescript]: https://www.typescriptlang.org

[license]: license

[author]: https://wooorm.com

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

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

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

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

[xss]: https://en.wikipedia.org/wiki/Cross-site_scripting

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

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

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

[node]: https://github.com/syntax-tree/mdast#nodes

[literal]: https://github.com/syntax-tree/mdast#literal

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

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

[api-void]: #_voidnode-parent

[api-assert]: #asserttree-parent

[api-literal]: #literalnode-parent

[api-parent]: #parenttree-parent

[api-wrap]: #wrapfn

[api-assertion-error]: #assertionerror

[unist-util-assert-void]: https://github.com/syntax-tree/unist-util-assert#_voidnode-parent

[unist-util-assert-wrap]: https://github.com/syntax-tree/unist-util-assert#wrapfn

[unist-util-assert-assertionerror]: https://github.com/syntax-tree/unist-util-assert#assertionerror

---
_Source: https://npm.io/package/mdast-util-assert · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._