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

utility to use headings as ranges in mdast
https://github.com/syntax-tree/mdast-util-heading-range

heading markdown mdast mdast-util syntax-tree unist util

Last synced: 3 months ago
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utility to use headings as ranges in mdast

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README 

        
# mdast-util-heading-range



[![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 find headings and replace the content in their section.



## Contents



*   [What is this?](#what-is-this)

*   [When should I use this?](#when-should-i-use-this)

*   [Install](#install)

*   [Use](#use)

*   [API](#api)

    *   [`headingRange(tree, test|options, handler)`](#headingrangetree-testoptions-handler)

    *   [`Handler`](#handler)

    *   [`Info`](#info)

    *   [`Options`](#options)

    *   [`Test`](#test)

    *   [`TestFunction`](#testfunction)

*   [Types](#types)

*   [Compatibility](#compatibility)

*   [Security](#security)

*   [Related](#related)

*   [Contribute](#contribute)

*   [License](#license)



## What is this?



This package is a utility that lets you find a certain heading, then takes the

content in their section (from it to the next heading of the same or lower

depth), 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.

For example, this utility is used by [`remark-toc`][remark-toc] to update the

above `Contents` heading.



A similar package, [`mdast-zone`][mdast-zone], does the same but uses comments

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-util-heading-range

```



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



```js

import {headingRange} from 'https://esm.sh/mdast-util-heading-range@4'

```



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



```html



  import {headingRange} from 'https://esm.sh/mdast-util-heading-range@4?bundle'



```



## Use



Say we have the following file, `example.md`:



```markdown

# Foo



Bar.



# Baz

```



…and a module `example.js`:



```js

import {read} from 'to-vfile'

import {remark} from 'remark'

import {headingRange} from 'mdast-util-heading-range'



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) {

    headingRange(tree, 'foo', function (start, nodes, end) {

      return [

        start,

        {type: 'paragraph', children: [{type: 'text', value: 'Qux.'}]},

        end

      ]

    })

  }

}

```



…now running `node example.js` yields:



```markdown

# Foo



Qux.



# Baz

```



## API



This package exports the identifier [`headingRange`][api-heading-range].

There is no default export.



### `headingRange(tree, test|options, handler)`



Search `tree` for a heading matching `test` and change its “section” with

`handler`.



A “section” ranges from the matched heading until the next heading of the

same or lower depth, or the end of the document.



If `ignoreFinalDefinitions: true`, final definitions “in” the section are

excluded.



###### Parameters



*   `tree` ([`Node`][node])

    — tree to change

*   `test` ([`Test`][api-test])

    — same as passing `{test: Test}`

*   `options` ([`Options`][api-options])

    — configuration

*   `handler` ([`Handler`][api-handler])

    — handle a section



###### Returns



Nothing (`undefined`).



### `Handler`



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



###### Parameters



*   `start` ([`Heading`][heading])

    — start of section (a heading node matching `test`)

*   `nodes` ([`Array`][node])

    — nodes between `start` and `end`

*   `end` ([`Node`][node] or `undefined`)

    — end of section, if any

*   `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.



### `Info`



Extra info (TypeScript type).



###### Fields



*   `parent` ([`Node`][node])

    — parent of the section

*   `start` (`number`)

    — index of `start` in `parent`

*   `end` (`number` or `undefined`)

    — index of `end` in `parent`



### `Options`



Configuration (TypeScript type).



###### Fields



*   `test` ([`Test`][api-test])

    — test for a heading

*   `ignoreFinalDefinitions` (`boolean`, default: `false`)

    — ignore final definitions otherwise in the section



### `Test`



Test for a heading (TypeScript type).



When `string`, wrapped in `new RegExp('^(' + value + ')$', 'i')`;

when `RegExp`, wrapped in `(value) => expression.test(value)`



###### Type



```ts

export type Test = RegExp | TestFunction | string

```



### `TestFunction`



Check if a node matches (TypeScript type).



###### Parameters



*   `value` (`string`)

    — plain-text heading

*   `node` ([`Heading`][heading])

    — heading node



###### Returns



Whether this is the heading that is searched for (`boolean`, optional).



## Types



This package is fully typed with [TypeScript][].

This package exports the types [`Handler`][api-handler],

[`Info`][api-info], [`Options`][api-options], [`Test`][api-test],

and [`TestFunction`][api-test-function].



## 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-heading-range@^4`, 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**][hast].

The following example shows how a script is injected that could run when loaded

in a browser.



```js

/** @type {import('mdast-util-heading-range').Handler} */

function handler(start, nodes, end) {

  return [start, {type: 'html', value: 'alert(1)'}, end]

}

```



Yields:



```markdown

# Foo



alert(1)



# Baz

```



Either do not use user input in `handler` or use

[`hast-util-santize`][hast-util-sanitize].



## Related



*   [`mdast-zone`](https://github.com/syntax-tree/mdast-zone)

    — similar but uses comments to mark the start and end of 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, organisation, or community you agree to

abide by its terms.



## License



[MIT][license] © [Titus Wormer][author]



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



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



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



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



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



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



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



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



[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



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



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



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



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



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



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



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



[remark-toc]: https://github.com/remarkjs/remark-toc



[api-heading-range]: #headingrangetree-testoptions-handler



[api-handler]: #handler



[api-options]: #options



[api-test]: #test



[api-test-function]: #testfunction



[api-info]: #info