595 lines
31 KiB
Plaintext
595 lines
31 KiB
Plaintext
# hast-util-from-html
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[![Build][build-badge]][build]
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[![Backers][backers-badge]][collective]
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[![Chat][chat-badge]][chat]
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[hast][] utility that turns HTML into a syntax tree.
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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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* [`fromHtml(value[, options])`](#fromhtmlvalue-options)
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* [`ErrorCode`](#errorcode)
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* [`ErrorSeverity`](#errorseverity)
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* [`OnError`](#onerror)
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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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* [Types](#types-2)
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* [Compatibility](#compatibility)
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* [Security](#security)
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* [Related](#related)
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* [Contribute](#contribute)
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* [License](#license)
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## What is this?
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This package is a utility that takes HTML input and turns it into a hast syntax
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tree.
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## When should I use this?
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If you want to handle syntax trees manually, use this.
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Use [`parse5`][parse5] instead when you just want to parse HTML and don’t care
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about [hast][].
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You can also use [`hast-util-from-parse5`][hast-util-from-parse5] and
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[`parse5`][parse5] yourself, or use the rehype plugin
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[`rehype-parse`][rehype-parse], which wraps this utility to also parse HTML at
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a higher-level (easier) abstraction.
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[`xast-util-from-xml`][xast-util-from-xml] can be used if you are dealing with
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XML instead of HTML.
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If you might run in a browser and prefer a ligher alternative, while not caring
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about positional info, parse errors, and consistency across browsers, use
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[`hast-util-from-html-isomorphic`][hast-util-from-html-isomorphic], which
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wraps this in Node and uses browser APIs otherwise.
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Finally you can use the utility [`hast-util-to-html`][hast-util-to-html] for
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the inverse of this utility.
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It turns hast into HTML.
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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 hast-util-from-html
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```
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In Deno with [`esm.sh`][esmsh]:
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```js
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import {fromHtml} from 'https://esm.sh/hast-util-from-html@2'
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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 {fromHtml} from 'https://esm.sh/hast-util-from-html@2?bundle'
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</script>
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```
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## Use
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```js
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import {fromHtml} from 'hast-util-from-html'
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const tree = fromHtml('<h1>Hello, world!</h1>', {fragment: true})
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console.log(tree)
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```
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Yields:
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```js
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{
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type: 'root',
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children: [
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{
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type: 'element',
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tagName: 'h1',
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properties: {},
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children: [Array],
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position: [Object]
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}
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],
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data: { quirksMode: false },
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position: {
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start: { line: 1, column: 1, offset: 0 },
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end: { line: 1, column: 23, offset: 22 }
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}
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}
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```
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## API
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This package exports the identifier [`fromHtml`][api-from-html].
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There is no default export.
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### `fromHtml(value[, options])`
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Turn serialized HTML into a hast tree.
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###### Parameters
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* `value` ([`Compatible`][compatible])
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— serialized HTML to parse
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* `options` ([`Options`][api-options], optional)
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— configuration
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###### Returns
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Tree ([`Root`][root]).
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### `ErrorCode`
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Known names of parse errors (TypeScript type).
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###### Types
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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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// … see readme on `options[key in ErrorCode]` above.
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```
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### `ErrorSeverity`
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Error severity (TypeScript type).
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###### Types
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```ts
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export type ErrorSeverity =
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// Turn the parse error off:
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| 0
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| false
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// Turn the parse error into a warning:
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| 1
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| true
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// Turn the parse error into an actual error: processing stops.
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| 2
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```
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### `OnError`
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Function called when encountering [HTML parse errors][parse-errors].
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###### Parameters
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* `error` ([`VFileMessage`][vfile-message])
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— message
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###### Returns
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Nothing (`void`).
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### `Options`
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Configuration (TypeScript type).
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##### Fields
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###### `options.space`
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Which space the document is in (`'html'` or `'svg'`, default: `'html'`).
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When an `<svg>` element is found in the HTML space, `hast-util-from-html`
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already automatically switches to and from the SVG space when entering and
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exiting it.
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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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> 👉 **Note**: make sure to set `fragment: true` if `space: 'svg'`.
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###### `options.verbose`
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Add extra positional info about attributes, start tags, and end tags
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(`boolean`, default: `false`).
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###### `options.fragment`
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Whether to parse as a fragment (`boolean`, default: `false`).
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The default is to expect a whole document.
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In document mode, unopened `html`, `head`, and `body` elements are opened.
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###### `options.onerror`
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Function called when encountering [HTML parse errors][parse-errors]
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([`OnError`][api-on-error], optional).
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###### `options[key in ErrorCode]`
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Specific parse errors can be configured by setting their identifiers (see
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[`ErrorCode`][api-error-code]) as keys directly in `options` to an
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[`ErrorSeverity`][api-error-severity] as value.
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The list of parse errors:
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<!-- parse-error start -->
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* `abandonedHeadElementChild` — unexpected metadata element after head ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/abandoned-head-element-child/index.html))
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* [`abruptClosingOfEmptyComment`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-abrupt-closing-of-empty-comment) — unexpected abruptly closed empty comment ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/abrupt-closing-of-empty-comment/index.html))
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* [`abruptDoctypePublicIdentifier`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-abrupt-doctype-public-identifier) — unexpected abruptly closed public identifier ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/abrupt-doctype-public-identifier/index.html))
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* [`abruptDoctypeSystemIdentifier`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-abrupt-doctype-system-identifier) — unexpected abruptly closed system identifier ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/abrupt-doctype-system-identifier/index.html))
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* [`absenceOfDigitsInNumericCharacterReference`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-absence-of-digits-in-numeric-character-reference) — unexpected non-digit at start of numeric character reference ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/absence-of-digits-in-numeric-character-reference/index.html))
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* [`cdataInHtmlContent`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-cdata-in-html-content) — unexpected CDATA section in HTML ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/cdata-in-html-content/index.html))
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* [`characterReferenceOutsideUnicodeRange`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-character-reference-outside-unicode-range) — unexpected too big numeric character reference ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/character-reference-outside-unicode-range/index.html))
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* `closingOfElementWithOpenChildElements` — unexpected closing tag with open child elements ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/closing-of-element-with-open-child-elements/index.html))
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* [`controlCharacterInInputStream`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-control-character-in-input-stream) — unexpected control character ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/control-character-in-input-stream/index.html))
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* [`controlCharacterReference`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-control-character-reference) — unexpected control character reference ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/control-character-reference/index.html))
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* `disallowedContentInNoscriptInHead` — disallowed content inside `<noscript>` in `<head>` ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/disallowed-content-in-noscript-in-head/index.html))
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* [`duplicateAttribute`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-duplicate-attribute) — unexpected duplicate attribute ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/duplicate-attribute/index.html))
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* [`endTagWithAttributes`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-end-tag-with-attributes) — unexpected attribute on closing tag ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/end-tag-with-attributes/index.html))
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* [`endTagWithTrailingSolidus`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-end-tag-with-trailing-solidus) — unexpected slash at end of closing tag ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/end-tag-with-trailing-solidus/index.html))
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* `endTagWithoutMatchingOpenElement` — unexpected unopened end tag ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/end-tag-without-matching-open-element/index.html))
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* [`eofBeforeTagName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-eof-before-tag-name) — unexpected end of file ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/eof-before-tag-name/index.html))
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* [`eofInCdata`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-eof-in-cdata) — unexpected end of file in CDATA ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/eof-in-cdata/index.html))
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* [`eofInComment`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-eof-in-comment) — unexpected end of file in comment ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/eof-in-comment/index.html))
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* [`eofInDoctype`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-eof-in-doctype) — unexpected end of file in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/eof-in-doctype/index.html))
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* `eofInElementThatCanContainOnlyText` — unexpected end of file in element that can only contain text ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/eof-in-element-that-can-contain-only-text/index.html))
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* [`eofInScriptHtmlCommentLikeText`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-eof-in-script-html-comment-like-text) — unexpected end of file in comment inside script ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/eof-in-script-html-comment-like-text/index.html))
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* [`eofInTag`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-eof-in-tag) — unexpected end of file in tag ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/eof-in-tag/index.html))
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* [`incorrectlyClosedComment`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-incorrectly-closed-comment) — incorrectly closed comment ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/incorrectly-closed-comment/index.html))
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* [`incorrectlyOpenedComment`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-incorrectly-opened-comment) — incorrectly opened comment ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/incorrectly-opened-comment/index.html))
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* [`invalidCharacterSequenceAfterDoctypeName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-invalid-character-sequence-after-doctype-name) — invalid sequence after doctype name ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/invalid-character-sequence-after-doctype-name/index.html))
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* [`invalidFirstCharacterOfTagName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-invalid-first-character-of-tag-name) — invalid first character in tag name ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/invalid-first-character-of-tag-name/index.html))
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* `misplacedDoctype` — misplaced doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/misplaced-doctype/index.html))
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* `misplacedStartTagForHeadElement` — misplaced `<head>` start tag ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/misplaced-start-tag-for-head-element/index.html))
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* [`missingAttributeValue`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-attribute-value) — missing attribute value ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-attribute-value/index.html))
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* `missingDoctype` — missing doctype before other content ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-doctype/index.html))
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* [`missingDoctypeName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-doctype-name) — missing doctype name ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-doctype-name/index.html))
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* [`missingDoctypePublicIdentifier`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-doctype-public-identifier) — missing public identifier in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-doctype-public-identifier/index.html))
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* [`missingDoctypeSystemIdentifier`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-doctype-system-identifier) — missing system identifier in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-doctype-system-identifier/index.html))
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* [`missingEndTagName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-end-tag-name) — missing name in end tag ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-end-tag-name/index.html))
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* [`missingQuoteBeforeDoctypePublicIdentifier`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-quote-before-doctype-public-identifier) — missing quote before public identifier in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-quote-before-doctype-public-identifier/index.html))
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* [`missingQuoteBeforeDoctypeSystemIdentifier`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-quote-before-doctype-system-identifier) — missing quote before system identifier in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-quote-before-doctype-system-identifier/index.html))
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* [`missingSemicolonAfterCharacterReference`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-semicolon-after-character-reference) — missing semicolon after character reference ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-semicolon-after-character-reference/index.html))
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* [`missingWhitespaceAfterDoctypePublicKeyword`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-whitespace-after-doctype-public-keyword) — missing whitespace after public identifier in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-whitespace-after-doctype-public-keyword/index.html))
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* [`missingWhitespaceAfterDoctypeSystemKeyword`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-whitespace-after-doctype-system-keyword) — missing whitespace after system identifier in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-whitespace-after-doctype-system-keyword/index.html))
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* [`missingWhitespaceBeforeDoctypeName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-whitespace-before-doctype-name) — missing whitespace before doctype name ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-whitespace-before-doctype-name/index.html))
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* [`missingWhitespaceBetweenAttributes`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-whitespace-between-attributes) — missing whitespace between attributes ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-whitespace-between-attributes/index.html))
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* [`missingWhitespaceBetweenDoctypePublicAndSystemIdentifiers`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-whitespace-between-doctype-public-and-system-identifiers) — missing whitespace between public and system identifiers in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/missing-whitespace-between-doctype-public-and-system-identifiers/index.html))
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* [`nestedComment`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-nested-comment) — unexpected nested comment ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/nested-comment/index.html))
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* `nestedNoscriptInHead` — unexpected nested `<noscript>` in `<head>` ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/nested-noscript-in-head/index.html))
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* `nonConformingDoctype` — unexpected non-conforming doctype declaration ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/non-conforming-doctype/index.html))
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* [`nonVoidHtmlElementStartTagWithTrailingSolidus`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-non-void-html-element-start-tag-with-trailing-solidus) — unexpected trailing slash on start tag of non-void element ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/non-void-html-element-start-tag-with-trailing-solidus/index.html))
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* [`noncharacterCharacterReference`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-noncharacter-character-reference) — unexpected noncharacter code point referenced by character reference ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/noncharacter-character-reference/index.html))
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* [`noncharacterInInputStream`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-noncharacter-in-input-stream) — unexpected noncharacter character ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/noncharacter-in-input-stream/index.html))
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* [`nullCharacterReference`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-null-character-reference) — unexpected NULL character referenced by character reference ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/null-character-reference/index.html))
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* `openElementsLeftAfterEof` — unexpected end of file ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/open-elements-left-after-eof/index.html))
|
||
* [`surrogateCharacterReference`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-surrogate-character-reference) — unexpected surrogate character referenced by character reference ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/surrogate-character-reference/index.html))
|
||
* [`surrogateInInputStream`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-surrogate-in-input-stream) — unexpected surrogate character
|
||
* [`unexpectedCharacterAfterDoctypeSystemIdentifier`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-unexpected-character-after-doctype-system-identifier) — invalid character after system identifier in doctype ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/unexpected-character-after-doctype-system-identifier/index.html))
|
||
* [`unexpectedCharacterInAttributeName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-unexpected-character-in-attribute-name) — unexpected character in attribute name ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/unexpected-character-in-attribute-name/index.html))
|
||
* [`unexpectedCharacterInUnquotedAttributeValue`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-unexpected-character-in-unquoted-attribute-value) — unexpected character in unquoted attribute value ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/unexpected-character-in-unquoted-attribute-value/index.html))
|
||
* [`unexpectedEqualsSignBeforeAttributeName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-unexpected-equals-sign-before-attribute-name) — unexpected equals sign before attribute name ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/unexpected-equals-sign-before-attribute-name/index.html))
|
||
* [`unexpectedNullCharacter`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-unexpected-null-character) — unexpected NULL character ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/unexpected-null-character/index.html))
|
||
* [`unexpectedQuestionMarkInsteadOfTagName`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-unexpected-question-mark-instead-of-tag-name) — unexpected question mark instead of tag name ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/unexpected-question-mark-instead-of-tag-name/index.html))
|
||
* [`unexpectedSolidusInTag`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-unexpected-solidus-in-tag) — unexpected slash in tag ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/unexpected-solidus-in-tag/index.html))
|
||
* [`unknownNamedCharacterReference`](https://html.spec.whatwg.org/multipage/parsing.html#parse-error-unknown-named-character-reference) — unexpected unknown named character reference ([example](https://github.com/syntax-tree/hast-util-from-html/blob/main/test/parse-error/unknown-named-character-reference/index.html))
|
||
|
||
<!-- parse-error end -->
|
||
|
||
## Examples
|
||
|
||
### Example: fragment versus document
|
||
|
||
The following example shows the difference between parsing as a document and
|
||
parsing as a fragment:
|
||
|
||
```js
|
||
import {fromHtml} from 'hast-util-from-html'
|
||
|
||
const doc = '<title>Hi!</title><h1>Hello!</h1>'
|
||
|
||
console.log(fromHtml(doc))
|
||
|
||
console.log(fromHtml(doc, {fragment: true}))
|
||
```
|
||
|
||
…yields (positional info and data omitted for brevity):
|
||
|
||
```js
|
||
{
|
||
type: 'root',
|
||
children: [
|
||
{type: 'element', tagName: 'html', properties: {}, children: [Array]}
|
||
]
|
||
}
|
||
```
|
||
|
||
```js
|
||
{
|
||
type: 'root',
|
||
children: [
|
||
{type: 'element', tagName: 'title', properties: {}, children: [Array]},
|
||
{type: 'element', tagName: 'h1', properties: {}, children: [Array]}
|
||
]
|
||
}
|
||
```
|
||
|
||
> 👉 **Note**: observe that when a whole document is expected (first example),
|
||
> missing elements are opened and closed.
|
||
|
||
### Example: whitespace around and inside `<html>`
|
||
|
||
The following example shows how whitespace is handled when around and directly
|
||
inside the `<html>` element:
|
||
|
||
```js
|
||
import {fromHtml} from 'hast-util-from-html'
|
||
import {inspect} from 'unist-util-inspect'
|
||
|
||
const doc = `<!doctype html>
|
||
<html lang=en>
|
||
<head>
|
||
<title>Hi!</title>
|
||
</head>
|
||
<body>
|
||
<h1>Hello!</h1>
|
||
</body>
|
||
</html>`
|
||
|
||
console.log(inspect(fromHtml(doc)))
|
||
```
|
||
|
||
…yields:
|
||
|
||
```txt
|
||
root[2] (1:1-9:8, 0-119)
|
||
│ data: {"quirksMode":false}
|
||
├─0 doctype (1:1-1:16, 0-15)
|
||
└─1 element<html>[3] (2:1-9:8, 16-119)
|
||
│ properties: {"lang":"en"}
|
||
├─0 element<head>[3] (3:3-5:10, 33-72)
|
||
│ │ properties: {}
|
||
│ ├─0 text "\n " (3:9-4:5, 39-44)
|
||
│ ├─1 element<title>[1] (4:5-4:23, 44-62)
|
||
│ │ │ properties: {}
|
||
│ │ └─0 text "Hi!" (4:12-4:15, 51-54)
|
||
│ └─2 text "\n " (4:23-5:3, 62-65)
|
||
├─1 text "\n " (5:10-6:3, 72-75)
|
||
└─2 element<body>[3] (6:3-8:10, 75-111)
|
||
│ properties: {}
|
||
├─0 text "\n " (6:9-7:5, 81-86)
|
||
├─1 element<h1>[1] (7:5-7:20, 86-101)
|
||
│ │ properties: {}
|
||
│ └─0 text "Hello!" (7:9-7:15, 90-96)
|
||
└─2 text "\n \n" (7:20-9:1, 101-112)
|
||
```
|
||
|
||
> 👉 **Note**: observe that the line ending before `<html>` is ignored, the line
|
||
> ending and two spaces before `<head>` is moved inside it, and the line ending
|
||
> after `</body>` is moved before it.
|
||
|
||
This behavior is described by the HTML standard (see the section 13.2.6.4.1
|
||
“The ‘initial’ insertion mode” and adjacent states) which we follow.
|
||
|
||
The changes to this meaningless whitespace should not matter, except when
|
||
formatting markup, in which case [`rehype-format`][rehype-format] can be used to
|
||
improve the source code.
|
||
|
||
### Example: parse errors
|
||
|
||
The following example shows how HTML parse errors can be enabled and configured:
|
||
|
||
```js
|
||
import {fromHtml} from 'hast-util-from-html'
|
||
|
||
const doc = `<!doctypehtml>
|
||
<title class="a" class="b">Hello…</title>
|
||
<h1/>World!</h1>`
|
||
|
||
fromHtml(doc, {
|
||
onerror: console.log,
|
||
missingWhitespaceBeforeDoctypeName: 2, // Mark one as a fatal error.
|
||
nonVoidHtmlElementStartTagWithTrailingSolidus: false // Ignore one.
|
||
})
|
||
```
|
||
|
||
…yields:
|
||
|
||
```txt
|
||
[1:10-1:10: Missing whitespace before doctype name] {
|
||
ancestors: undefined,
|
||
cause: undefined,
|
||
column: 10,
|
||
fatal: true,
|
||
line: 1,
|
||
place: {
|
||
start: { line: 1, column: 10, offset: 9 },
|
||
end: { line: 1, column: 10, offset: 9 }
|
||
},
|
||
reason: 'Missing whitespace before doctype name',
|
||
ruleId: 'missing-whitespace-before-doctype-name',
|
||
source: 'hast-util-from-html',
|
||
note: 'Unexpected `h`. Expected ASCII whitespace instead',
|
||
url: 'https://html.spec.whatwg.org/multipage/parsing.html#parse-error-missing-whitespace-before-doctype-name'
|
||
}
|
||
[2:23-2:23: Unexpected duplicate attribute] {
|
||
ancestors: undefined,
|
||
cause: undefined,
|
||
column: 23,
|
||
fatal: false,
|
||
line: 2,
|
||
place: {
|
||
start: { line: 2, column: 23, offset: 37 },
|
||
end: { line: 2, column: 23, offset: 37 }
|
||
},
|
||
reason: 'Unexpected duplicate attribute',
|
||
ruleId: 'duplicate-attribute',
|
||
source: 'hast-util-from-html',
|
||
note: 'Unexpectedly double attribute. Expected attributes to occur only once',
|
||
url: 'https://html.spec.whatwg.org/multipage/parsing.html#parse-error-duplicate-attribute'
|
||
}
|
||
```
|
||
|
||
> 🧑🏫 **Info**: messages in unified are warnings instead of errors.
|
||
> Other linters (such as ESLint) almost always use errors.
|
||
> Why?
|
||
> Those tools *only* check code style.
|
||
> They don’t generate, transform, and format code, which is what we focus on,
|
||
> too.
|
||
> Errors in unified mean the same as an exception in your JavaScript code: a
|
||
> crash.
|
||
> That’s why we use warnings instead, because we can continue doing work.
|
||
|
||
## Syntax
|
||
|
||
HTML is parsed according to WHATWG HTML (the living standard), which is also
|
||
followed by browsers such as Chrome and Firefox.
|
||
|
||
## Types
|
||
|
||
This package is fully typed with [TypeScript][].
|
||
It exports the additional types
|
||
[`ErrorCode`][api-error-code], [`ErrorSeverity`][api-error-severity],
|
||
[`OnError`][api-on-error], and [`Options`][api-options].
|
||
|
||
## 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, `hast-util-from-html@^2`,
|
||
compatible with Node.js 16.
|
||
|
||
## Security
|
||
|
||
Parsing HTML is safe but using user-provided content can open you up to a
|
||
[cross-site scripting (XSS)][xss] attack.
|
||
Use [`hast-util-santize`][hast-util-sanitize] to make the hast tree safe.
|
||
|
||
## Related
|
||
|
||
* [`hast-util-to-html`](https://github.com/syntax-tree/hast-util-to-html)
|
||
— serialize hast
|
||
* [`hast-util-sanitize`](https://github.com/syntax-tree/hast-util-sanitize)
|
||
— sanitize hast
|
||
* [`xast-util-from-xml`][xast-util-from-xml]
|
||
— parse XML
|
||
|
||
## 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/hast-util-from-html/workflows/main/badge.svg
|
||
|
||
[build]: https://github.com/syntax-tree/hast-util-from-html/actions
|
||
|
||
[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/hast-util-from-html.svg
|
||
|
||
[coverage]: https://codecov.io/github/syntax-tree/hast-util-from-html
|
||
|
||
[downloads-badge]: https://img.shields.io/npm/dm/hast-util-from-html.svg
|
||
|
||
[downloads]: https://www.npmjs.com/package/hast-util-from-html
|
||
|
||
[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=hast-util-from-html
|
||
|
||
[size]: https://bundlejs.com/?q=hast-util-from-html
|
||
|
||
[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
|
||
|
||
[hast]: https://github.com/syntax-tree/hast
|
||
|
||
[root]: https://github.com/syntax-tree/hast#root
|
||
|
||
[hast-util-sanitize]: https://github.com/syntax-tree/hast-util-sanitize
|
||
|
||
[hast-util-from-parse5]: https://github.com/syntax-tree/hast-util-from-parse5
|
||
|
||
[hast-util-to-html]: https://github.com/syntax-tree/hast-util-to-html
|
||
|
||
[xast-util-from-xml]: https://github.com/syntax-tree/xast-util-from-xml
|
||
|
||
[rehype-parse]: https://github.com/rehypejs/rehype/tree/main/packages/rehype-parse#readme
|
||
|
||
[rehype-format]: https://github.com/rehypejs/rehype-format
|
||
|
||
[parse5]: https://github.com/inikulin/parse5
|
||
|
||
[parse-errors]: https://html.spec.whatwg.org/multipage/parsing.html#parse-errors
|
||
|
||
[vfile-message]: https://github.com/vfile/vfile-message#vfilemessagereason-place-origin
|
||
|
||
[hast-util-from-html-isomorphic]: https://github.com/syntax-tree/hast-util-from-html-isomorphic
|
||
|
||
[compatible]: https://github.com/vfile/vfile#compatible
|
||
|
||
[api-from-html]: #fromhtmlvalue-options
|
||
|
||
[api-error-code]: #errorcode
|
||
|
||
[api-error-severity]: #errorseverity
|
||
|
||
[api-on-error]: #onerror
|
||
|
||
[api-options]: #options
|