Mdast-util-assert NPM

mdast-util-assert

mdast utility to assert trees.

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, does the same but for any unist node.

Install

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

npm install mdast-util-assert

In Deno with esm.sh:

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

In browsers with esm.sh:

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

Use

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, assert, literal, parent, and wrap. There is no default export.

`assert(tree[, parent])`

Assert that tree is a valid mdast Node.

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

Supports unknown mdast nodes.

Parameters

tree (unknown) — thing to assert
parent (Parent, optional) — optional, valid parent

Returns

Nothing.

Throws

When tree (or its descendants) is not an mdast node (AssertionError).

`parent(tree[, parent])`

Assert that tree is a valid mdast Parent.

All children will be asserted too.

Supports unknown mdast nodes.

Parameters

tree (unknown) — thing to assert
parent (Parent, optional) — optional, valid parent

Returns

Nothing.

Throws

When tree is not a parent or its descendants are not nodes (AssertionError)

`literal(node[, parent])`

Assert that node is a valid mdast Literal.

Supports unknown mdast nodes.

Parameters

node (unknown) — thing to assert
parent (Parent, optional) — optional, valid parent

Returns

Nothing.

Throws

When node is not an mdast literal (AssertionError).

Types

This package is fully typed with TypeScript. It exports the additional type AssertionError.

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.