587 lines
17 KiB
Plaintext
587 lines
17 KiB
Plaintext
# rehype-parse
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[![Build][build-badge]][build]
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[![Coverage][coverage-badge]][coverage]
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[![Downloads][downloads-badge]][downloads]
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[![Size][size-badge]][size]
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[![Sponsors][sponsors-badge]][collective]
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[![Backers][backers-badge]][collective]
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[![Chat][chat-badge]][chat]
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**[rehype][]** plugin to add support for parsing from HTML.
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## Contents
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* [What is this?](#what-is-this)
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* [When should I use this?](#when-should-i-use-this)
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* [Install](#install)
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* [Use](#use)
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* [API](#api)
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* [`unified().use(rehypeParse[, options])`](#unifieduserehypeparse-options)
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* [`ErrorCode`](#errorcode)
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* [`ErrorSeverity`](#errorseverity)
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* [`Options`](#options)
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* [Examples](#examples)
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* [Example: fragment versus document](#example-fragment-versus-document)
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* [Example: whitespace around and inside `<html>`](#example-whitespace-around-and-inside-html)
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* [Example: parse errors](#example-parse-errors)
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* [Syntax](#syntax)
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* [Syntax tree](#syntax-tree)
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* [Types](#types)
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* [Compatibility](#compatibility)
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* [Security](#security)
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* [Contribute](#contribute)
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* [Sponsor](#sponsor)
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* [License](#license)
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## What is this?
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This package is a [unified][] ([rehype][]) plugin that defines how to take HTML
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as input and turn it into a syntax tree.
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When it’s used, HTML can be parsed and other rehype plugins can be used after
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it.
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See [the monorepo readme][rehype] for info on what the rehype ecosystem is.
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## When should I use this?
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This plugin adds support to unified for parsing HTML.
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If you also need to serialize HTML, you can alternatively use
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[`rehype`][rehype-core], which combines unified, this plugin, and
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[`rehype-stringify`][rehype-stringify].
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When you are in a browser, trust your content, don’t need positional info, and
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value a smaller bundle size, you can use [`rehype-dom-parse`][rehype-dom-parse]
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instead.
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If you don’t use plugins and want to access the syntax tree, you can directly
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use [`hast-util-from-html`][hast-util-from-html], which is used inside this
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plugin.
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rehype focusses on making it easier to transform content by abstracting such
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internals away.
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## Install
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This package is [ESM only][esm].
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In Node.js (version 16+), install with [npm][]:
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```sh
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npm install rehype-parse
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```
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In Deno with [`esm.sh`][esmsh]:
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```js
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import rehypeParse from 'https://esm.sh/rehype-parse@9'
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```
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In browsers with [`esm.sh`][esmsh]:
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```html
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<script type="module">
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import rehypeParse from 'https://esm.sh/rehype-parse@9?bundle'
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</script>
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```
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## Use
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Say we have the following module `example.js`:
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```js
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import rehypeParse from 'rehype-parse'
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import rehypeRemark from 'rehype-remark'
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import remarkStringify from 'remark-stringify'
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import {unified} from 'unified'
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const file = await unified()
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.use(rehypeParse)
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.use(rehypeRemark)
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.use(remarkStringify)
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.process('<h1>Hello, world!</h1>')
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console.log(String(file))
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```
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…running that with `node example.js` yields:
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```markdown
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# Hello, world!
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```
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## API
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This package exports no identifiers.
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The default export is [`rehypeParse`][api-rehype-parse].
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### `unified().use(rehypeParse[, options])`
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Plugin to add support for parsing from HTML.
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###### Parameters
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* `options` ([`Options`][api-options], optional)
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— configuration
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###### Returns
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Nothing (`undefined`).
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### `ErrorCode`
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Known names of [parse errors][parse-errors] (TypeScript type).
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For a bit more info on each error, see
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[`hast-util-from-html`][hast-util-from-html-errors].
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###### Type
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```ts
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type ErrorCode =
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| 'abandonedHeadElementChild'
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| 'abruptClosingOfEmptyComment'
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| 'abruptDoctypePublicIdentifier'
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| 'abruptDoctypeSystemIdentifier'
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| 'absenceOfDigitsInNumericCharacterReference'
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| 'cdataInHtmlContent'
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| 'characterReferenceOutsideUnicodeRange'
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| 'closingOfElementWithOpenChildElements'
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| 'controlCharacterInInputStream'
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| 'controlCharacterReference'
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| 'disallowedContentInNoscriptInHead'
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| 'duplicateAttribute'
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| 'endTagWithAttributes'
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| 'endTagWithTrailingSolidus'
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| 'endTagWithoutMatchingOpenElement'
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| 'eofBeforeTagName'
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| 'eofInCdata'
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| 'eofInComment'
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| 'eofInDoctype'
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| 'eofInElementThatCanContainOnlyText'
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| 'eofInScriptHtmlCommentLikeText'
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| 'eofInTag'
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| 'incorrectlyClosedComment'
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| 'incorrectlyOpenedComment'
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| 'invalidCharacterSequenceAfterDoctypeName'
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| 'invalidFirstCharacterOfTagName'
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| 'misplacedDoctype'
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| 'misplacedStartTagForHeadElement'
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| 'missingAttributeValue'
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| 'missingDoctype'
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| 'missingDoctypeName'
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| 'missingDoctypePublicIdentifier'
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| 'missingDoctypeSystemIdentifier'
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| 'missingEndTagName'
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| 'missingQuoteBeforeDoctypePublicIdentifier'
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| 'missingQuoteBeforeDoctypeSystemIdentifier'
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| 'missingSemicolonAfterCharacterReference'
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| 'missingWhitespaceAfterDoctypePublicKeyword'
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| 'missingWhitespaceAfterDoctypeSystemKeyword'
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| 'missingWhitespaceBeforeDoctypeName'
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| 'missingWhitespaceBetweenAttributes'
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| 'missingWhitespaceBetweenDoctypePublicAndSystemIdentifiers'
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| 'nestedComment'
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| 'nestedNoscriptInHead'
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| 'nonConformingDoctype'
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| 'nonVoidHtmlElementStartTagWithTrailingSolidus'
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| 'noncharacterCharacterReference'
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| 'noncharacterInInputStream'
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| 'nullCharacterReference'
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| 'openElementsLeftAfterEof'
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| 'surrogateCharacterReference'
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| 'surrogateInInputStream'
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| 'unexpectedCharacterAfterDoctypeSystemIdentifier'
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| 'unexpectedCharacterInAttributeName'
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| 'unexpectedCharacterInUnquotedAttributeValue'
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| 'unexpectedEqualsSignBeforeAttributeName'
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| 'unexpectedNullCharacter'
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| 'unexpectedQuestionMarkInsteadOfTagName'
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| 'unexpectedSolidusInTag'
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| 'unknownNamedCharacterReference'
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```
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### `ErrorSeverity`
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Error severity (TypeScript type).
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* `0` or `false`
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— turn the parse error off
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* `1` or `true`
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— turn the parse error into a warning
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* `2`
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— turn the parse error into an actual error: processing stops
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###### Type
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```ts
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type ErrorSeverity = boolean | 0 | 1 | 2
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```
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### `Options`
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Configuration (TypeScript type).
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> 👉 **Note**: this is not an XML parser.
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> It supports SVG as embedded in HTML.
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> It does not support the features available in XML.
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> Passing SVG files might break but fragments of modern SVG should be fine.
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> Use [`xast-util-from-xml`][xast-util-from-xml] to parse XML.
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###### Fields
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* `fragment` (`boolean`, default: `false`)
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— whether to parse as a fragment; by default unopened `html`, `head`, and
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`body` elements are opened
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* `emitParseErrors` (`boolean`, default: `false`)
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— whether to emit [parse errors][parse-errors] while parsing
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* `space` (`'html'` or `'svg'`, default: `'html'`)
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— which space the document is in
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* `verbose` (`boolean`, default: `false`)
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— add extra positional info about attributes, start tags, and end tags
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* [`[key in ErrorCode]`][api-error-code]
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([`ErrorSeverity`][api-error-severity], default: `1` if
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`options.emitParseErrors`, otherwise `0`)
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— configure specific [parse errors][parse-errors]
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## Examples
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### Example: fragment versus document
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The following example shows the difference between parsing as a document and
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parsing as a fragment:
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```js
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import rehypeParse from 'rehype-parse'
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import rehypeStringify from 'rehype-stringify'
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import {unified} from 'unified'
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const doc = '<title>Hi!</title><h1>Hello!</h1>'
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console.log(
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String(
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await unified()
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.use(rehypeParse, {fragment: true})
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.use(rehypeStringify)
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.process(doc)
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)
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)
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console.log(
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String(
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await unified()
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.use(rehypeParse, {fragment: false})
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.use(rehypeStringify)
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.process(doc)
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)
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)
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```
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…yields:
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```html
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<title>Hi!</title><h1>Hello!</h1>
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```
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```html
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<html><head><title>Hi!</title></head><body><h1>Hello!</h1></body></html>
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```
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> 👉 **Note**: observe that when a whole document is expected (second example),
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> missing elements are opened and closed.
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### Example: whitespace around and inside `<html>`
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The following example shows how whitespace is handled when around and directly
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inside the `<html>` element:
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```js
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import rehypeParse from 'rehype-parse'
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import rehypeStringify from 'rehype-stringify'
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import {unified} from 'unified'
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const doc = `<!doctype html>
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<html lang=en>
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<head>
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<title>Hi!</title>
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</head>
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<body>
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<h1>Hello!</h1>
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</body>
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</html>`
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console.log(
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String(await unified().use(rehypeParse).use(rehypeStringify).process(doc))
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)
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```
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…yields (where `␠` represents a space character):
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```html
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<!doctype html><html lang="en"><head>
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<title>Hi!</title>
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</head>
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<body>
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<h1>Hello!</h1>
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␠␠
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</body></html>
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```
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> 👉 **Note**: observe that the line ending before `<html>` is ignored, the line
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> ending and two spaces before `<head>` is moved inside it, and the line ending
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> after `</body>` is moved before it.
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This behavior is described by the HTML standard (see the section 13.2.6.4.1
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“The ‘initial’ insertion mode” and adjacent states) which rehype follows.
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The changes to this meaningless whitespace should not matter, except when
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formatting markup, in which case [`rehype-format`][rehype-format] can be used to
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improve the source code.
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### Example: parse errors
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The following example shows how HTML parse errors can be enabled and configured:
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```js
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import rehypeParse from 'rehype-parse'
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import rehypeStringify from 'rehype-stringify'
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import {unified} from 'unified'
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import {reporter} from 'vfile-reporter'
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const file = await unified()
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.use(rehypeParse, {
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emitParseErrors: true, // Emit all.
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missingWhitespaceBeforeDoctypeName: 2, // Mark one as a fatal error.
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nonVoidHtmlElementStartTagWithTrailingSolidus: false // Ignore one.
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})
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.use(rehypeStringify).process(`<!doctypehtml>
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<title class="a" class="b">Hello…</title>
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<h1/>World!</h1>`)
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console.log(reporter(file))
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```
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…yields:
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```html
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1:10-1:10 error Missing whitespace before doctype name missing-whitespace-before-doctype-name hast-util-from-html
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2:23-2:23 warning Unexpected duplicate attribute duplicate-attribute hast-util-from-html
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2 messages (✖ 1 error, ⚠ 1 warning)
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```
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> 🧑🏫 **Info**: messages in unified are warnings instead of errors.
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> Other linters (such as ESLint) almost always use errors.
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> Why?
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> Those tools *only* check code style.
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> They don’t generate, transform, and format code, which is what rehype and
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> unified focus on, too.
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> Errors in unified mean the same as an exception in your JavaScript code: a
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> crash.
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> That’s why we use warnings instead, because we continue checking more HTML and
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> continue running more plugins.
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## Syntax
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HTML is parsed according to WHATWG HTML (the living standard), which is also
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followed by all browsers.
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## Syntax tree
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The syntax tree format used in rehype is [hast][].
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## Types
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This package is fully typed with [TypeScript][].
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It exports the additional types [`ErrorCode`][api-error-code],
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[`ErrorSeverity`][api-error-severity], and
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[`Options`][api-options].
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## Compatibility
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Projects maintained by the unified collective are compatible with maintained
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versions of Node.js.
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When we cut a new major release, we drop support for unmaintained versions of
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Node.
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This means we try to keep the current release line, `rehype-parse@^9`,
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compatible with Node.js 16.
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## Security
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As **rehype** works on HTML and improper use of HTML can open you up to a
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[cross-site scripting (XSS)][xss] attack, use of rehype can also be unsafe.
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Use [`rehype-sanitize`][rehype-sanitize] to make the tree safe.
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Use of rehype plugins could also open you up to other attacks.
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Carefully assess each plugin and the risks involved in using them.
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For info on how to submit a report, see our [security policy][security].
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## Contribute
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See [`contributing.md`][contributing] in [`rehypejs/.github`][health] for ways
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to get started.
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See [`support.md`][support] for ways to get help.
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This project has a [code of conduct][coc].
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By interacting with this repository, organization, or community you agree to
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abide by its terms.
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## Sponsor
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Support this effort and give back by sponsoring on [OpenCollective][collective]!
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<table>
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<tr valign="middle">
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<td width="20%" align="center" rowspan="2" colspan="2">
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<a href="https://vercel.com">Vercel</a><br><br>
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<a href="https://vercel.com"><img src="https://avatars1.githubusercontent.com/u/14985020?s=256&v=4" width="128"></a>
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</td>
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<td width="20%" align="center" rowspan="2" colspan="2">
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<a href="https://motif.land">Motif</a><br><br>
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<a href="https://motif.land"><img src="https://avatars1.githubusercontent.com/u/74457950?s=256&v=4" width="128"></a>
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</td>
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<td width="20%" align="center" rowspan="2" colspan="2">
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<a href="https://www.hashicorp.com">HashiCorp</a><br><br>
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||
<a href="https://www.hashicorp.com"><img src="https://avatars1.githubusercontent.com/u/761456?s=256&v=4" width="128"></a>
|
||
</td>
|
||
<td width="20%" align="center" rowspan="2" colspan="2">
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||
<a href="https://www.gitbook.com">GitBook</a><br><br>
|
||
<a href="https://www.gitbook.com"><img src="https://avatars1.githubusercontent.com/u/7111340?s=256&v=4" width="128"></a>
|
||
</td>
|
||
<td width="20%" align="center" rowspan="2" colspan="2">
|
||
<a href="https://www.gatsbyjs.org">Gatsby</a><br><br>
|
||
<a href="https://www.gatsbyjs.org"><img src="https://avatars1.githubusercontent.com/u/12551863?s=256&v=4" width="128"></a>
|
||
</td>
|
||
</tr>
|
||
<tr valign="middle">
|
||
</tr>
|
||
<tr valign="middle">
|
||
<td width="20%" align="center" rowspan="2" colspan="2">
|
||
<a href="https://www.netlify.com">Netlify</a><br><br>
|
||
<!--OC has a sharper image-->
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||
<a href="https://www.netlify.com"><img src="https://images.opencollective.com/netlify/4087de2/logo/256.png" width="128"></a>
|
||
</td>
|
||
<td width="10%" align="center">
|
||
<a href="https://www.coinbase.com">Coinbase</a><br><br>
|
||
<a href="https://www.coinbase.com"><img src="https://avatars1.githubusercontent.com/u/1885080?s=256&v=4" width="64"></a>
|
||
</td>
|
||
<td width="10%" align="center">
|
||
<a href="https://themeisle.com">ThemeIsle</a><br><br>
|
||
<a href="https://themeisle.com"><img src="https://avatars1.githubusercontent.com/u/58979018?s=128&v=4" width="64"></a>
|
||
</td>
|
||
<td width="10%" align="center">
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||
<a href="https://expo.io">Expo</a><br><br>
|
||
<a href="https://expo.io"><img src="https://avatars1.githubusercontent.com/u/12504344?s=128&v=4" width="64"></a>
|
||
</td>
|
||
<td width="10%" align="center">
|
||
<a href="https://boostnote.io">Boost Note</a><br><br>
|
||
<a href="https://boostnote.io"><img src="https://images.opencollective.com/boosthub/6318083/logo/128.png" width="64"></a>
|
||
</td>
|
||
<td width="10%" align="center">
|
||
<a href="https://markdown.space">Markdown Space</a><br><br>
|
||
<a href="https://markdown.space"><img src="https://images.opencollective.com/markdown-space/e1038ed/logo/128.png" width="64"></a>
|
||
</td>
|
||
<td width="10%" align="center">
|
||
<a href="https://www.holloway.com">Holloway</a><br><br>
|
||
<a href="https://www.holloway.com"><img src="https://avatars1.githubusercontent.com/u/35904294?s=128&v=4" width="64"></a>
|
||
</td>
|
||
<td width="10%"></td>
|
||
<td width="10%"></td>
|
||
</tr>
|
||
<tr valign="middle">
|
||
<td width="100%" align="center" colspan="8">
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<br>
|
||
<a href="https://opencollective.com/unified"><strong>You?</strong></a>
|
||
<br><br>
|
||
</td>
|
||
</tr>
|
||
</table>
|
||
|
||
## License
|
||
|
||
[MIT][license] © [Titus Wormer][author]
|
||
|
||
<!-- Definitions -->
|
||
|
||
[build-badge]: https://github.com/rehypejs/rehype/workflows/main/badge.svg
|
||
|
||
[build]: https://github.com/rehypejs/rehype/actions
|
||
|
||
[coverage-badge]: https://img.shields.io/codecov/c/github/rehypejs/rehype.svg
|
||
|
||
[coverage]: https://codecov.io/github/rehypejs/rehype
|
||
|
||
[downloads-badge]: https://img.shields.io/npm/dm/rehype-parse.svg
|
||
|
||
[downloads]: https://www.npmjs.com/package/rehype-parse
|
||
|
||
[size-badge]: https://img.shields.io/bundlejs/size/rehype-parse
|
||
|
||
[size]: https://bundlejs.com/?q=rehype-parse
|
||
|
||
[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/rehypejs/rehype/discussions
|
||
|
||
[security]: https://github.com/rehypejs/.github/blob/main/security.md
|
||
|
||
[health]: https://github.com/rehypejs/.github
|
||
|
||
[contributing]: https://github.com/rehypejs/.github/blob/main/contributing.md
|
||
|
||
[support]: https://github.com/rehypejs/.github/blob/main/support.md
|
||
|
||
[coc]: https://github.com/rehypejs/.github/blob/main/code-of-conduct.md
|
||
|
||
[license]: https://github.com/rehypejs/rehype/blob/main/license
|
||
|
||
[author]: https://wooorm.com
|
||
|
||
[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
|
||
|
||
[npm]: https://docs.npmjs.com/cli/install
|
||
|
||
[esmsh]: https://esm.sh
|
||
|
||
[unified]: https://github.com/unifiedjs/unified
|
||
|
||
[rehype]: https://github.com/rehypejs/rehype
|
||
|
||
[hast]: https://github.com/syntax-tree/hast
|
||
|
||
[xss]: https://en.wikipedia.org/wiki/Cross-site_scripting
|
||
|
||
[typescript]: https://www.typescriptlang.org
|
||
|
||
[hast-util-from-html]: https://github.com/syntax-tree/hast-util-from-html
|
||
|
||
[hast-util-from-html-errors]: https://github.com/syntax-tree/hast-util-from-html#optionskey-in-errorcode
|
||
|
||
[xast-util-from-xml]: https://github.com/syntax-tree/xast-util-from-xml
|
||
|
||
[rehype-dom-parse]: https://github.com/rehypejs/rehype-dom/tree/main/packages/rehype-dom-parse
|
||
|
||
[rehype-format]: https://github.com/rehypejs/rehype-format
|
||
|
||
[rehype-sanitize]: https://github.com/rehypejs/rehype-sanitize
|
||
|
||
[parse-errors]: https://html.spec.whatwg.org/multipage/parsing.html#parse-errors
|
||
|
||
[rehype-core]: ../rehype/
|
||
|
||
[rehype-stringify]: ../rehype-stringify/
|
||
|
||
[api-error-code]: #errorcode
|
||
|
||
[api-error-severity]: #errorseverity
|
||
|
||
[api-options]: #options
|
||
|
||
[api-rehype-parse]: #unifieduserehypeparse-options
|