mdast-zone

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[mdast][] utility to find two comments and replace the content in them.

Contents

* What is this?
* When should I use this?
* Install
* Use
* API
* zone(tree, name, handler)
* Handler
* Info
* Types
* Compatibility
* Security
* Related
* Contribute
* License

What is this?

This package is a utility that lets you find certain comments, then takes the
content between them, and calls a given handler with the result, so that you can
change or replace things.

When should I use this?

This utility is typically useful when you have certain sections that can be
generated.
Comments are a hidden part of markdown, so they can be used as processing
instructions.
You can use those comments to define what content to change or replace.

A similar package, [mdast-util-heading-range][mdast-util-heading-range], does
the same but uses a heading to mark the start and end of sections.

Install

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

``sh
npm install mdast-zone
`

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

`js
import {zone} from 'https://esm.sh/mdast-zone@6'
`

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

`html

`

Use

Say we have the following file, example.md:

`markdown


Foo


`

…and a module example.js:

`js
import {zone} from 'mdast-zone'
import {remark} from 'remark'
import {read} from 'to-vfile'

const file = await remark()
.use(myPluginThatReplacesFoo)
.process(await read('example.md'))

console.log(String(file))

/* @type {import('unified').Plugin<[], import('mdast').Root>} /
function myPluginThatReplacesFoo() {
return function (tree) {
zone(tree, 'foo', function (start, nodes, end) {
return [
start,
{type: 'paragraph', children: [{type: 'text', value: 'Bar.'}]},
end
]
})
}
}
`

…now running node example.js yields:

`markdown


Bar.


`

API

This package exports the identifier [zone][api-zone].
There is no default export.

$3

Search tree for a start and end comments matching name and change their
“section” with handler.

###### Parameters

* tree ([Node][node])
— tree to change
* name (string)
— comment name to look for
* handler ([Handler][api-handler])
— handle a section

###### Returns

Nothing (undefined).

$3

Callback called when a section is found (TypeScript type).

###### Parameters

* start ([Node][node])
— start of section
* nodes ([Array][node])
— nodes between start and end
* end ([Node][node])
— end of section
* info ([Info][api-info])
— extra info

###### Returns

Results (Array, optional).

If nothing is returned, nothing will be changed.
If an array of nodes (can include null and undefined) is returned, the
original section will be replaced by those nodes.

$3

Extra info (TypeScript type).

###### Fields

* parent ([Node][node])
— parent of the section
* start (number)
— index of start in parent
* end (number)
— index of end in parent

Types

This package is fully typed with [TypeScript][].
It exports the additional types [Handler][api-handler] and
[Info][api-info].

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-zone@^6,
compatible with Node.js 16.

Security

Improper use of handler can open you up to a [cross-site scripting (XSS)][xss]
attack as the value it returns is injected into the syntax tree.
This can become a problem if the tree is later transformed to [hast][].
The following example shows how a script is injected that could run when loaded
in a browser.

`js
function handler(start, nodes, end) {
return [start, {type: 'html', value: ''}, end]
}
`

Yields:

`markdown



`

Either do not use user input or use [hast-util-santize][hast-util-sanitize].

Related

* mdast-util-heading-range
— similar but uses headings to mark sections

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]

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

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

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

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

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

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

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

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

[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

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

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

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

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

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

[api-zone]: #zonetree-name-handler

[api-handler]: #handler

[api-info]: #info