` element (which could be changed with\n `data.hName`), with its children mapped from mdast to hast as well\n\nThis behavior can be changed by passing an `unknownHandler`.\n\n### `FootnoteBackContentTemplate`\n\nGenerate content for the backreference dynamically.\n\nFor the following markdown:\n\n```markdown\nAlpha[^micromark], bravo[^micromark], and charlie[^remark].\n\n[^remark]: things about remark\n[^micromark]: things about micromark\n```\n\nThis function will be called with:\n\n* `0` and `0` for the backreference from `things about micromark` to\n `alpha`, as it is the first used definition, and the first call to it\n* `0` and `1` for the backreference from `things about micromark` to\n `bravo`, as it is the first used definition, and the second call to it\n* `1` and `0` for the backreference from `things about remark` to\n `charlie`, as it is the second used definition\n\n###### Parameters\n\n* `referenceIndex` (`number`)\n — index of the definition in the order that they are first referenced,\n 0-indexed\n* `rereferenceIndex` (`number`)\n — index of calls to the same definition, 0-indexed\n\n###### Returns\n\nContent for the backreference when linking back from definitions to their\nreference (`Array`, `ElementContent`, or `string`).\n\n### `FootnoteBackLabelTemplate`\n\nGenerate a back label dynamically.\n\nFor the following markdown:\n\n```markdown\nAlpha[^micromark], bravo[^micromark], and charlie[^remark].\n\n[^remark]: things about remark\n[^micromark]: things about micromark\n```\n\nThis function will be called with:\n\n* `0` and `0` for the backreference from `things about micromark` to\n `alpha`, as it is the first used definition, and the first call to it\n* `0` and `1` for the backreference from `things about micromark` to\n `bravo`, as it is the first used definition, and the second call to it\n* `1` and `0` for the backreference from `things about remark` to\n `charlie`, as it is the second used definition\n\n###### Parameters\n\n* `referenceIndex` (`number`)\n — index of the definition in the order that they are first referenced,\n 0-indexed\n* `rereferenceIndex` (`number`)\n — index of calls to the same definition, 0-indexed\n\n###### Returns\n\nBack label to use when linking back from definitions to their reference\n(`string`).\n\n### `Handler`\n\nHandle a node (TypeScript type).\n\n###### Parameters\n\n* `state` ([`State`][api-state])\n — info passed around\n* `node` ([`MdastNode`][mdast-node])\n — node to handle\n* `parent` ([`MdastNode | undefined`][mdast-node])\n — parent of `node`\n\n###### Returns\n\nResult ([`Array | HastNode | undefined`][hast-node]).\n\n### `Handlers`\n\nHandle nodes (TypeScript type).\n\n###### Type\n\n```ts\ntype Handlers = Partial>\n```\n\n### `Options`\n\nConfiguration (TypeScript type).\n\n###### Fields\n\n* `allowDangerousHtml` (`boolean`, default: `false`)\n — whether to persist raw HTML in markdown in the hast tree\n* `clobberPrefix` (`string`, default: `'user-content-'`)\n — prefix to use before the `id` property on footnotes to prevent them from\n *clobbering*\n* `file` ([`VFile`][vfile], optional)\n — corresponding virtual file representing the input document\n* `footnoteBackContent`\n ([`FootnoteBackContentTemplate`][api-footnote-back-content-template]\n or `string`, default:\n [`defaultFootnoteBackContent`][api-default-footnote-back-content])\n — content of the backreference back to references\n* `footnoteBackLabel`\n ([`FootnoteBackLabelTemplate`][api-footnote-back-label-template]\n or `string`, default:\n [`defaultFootnoteBackLabel`][api-default-footnote-back-label])\n — label to describe the backreference back to references\n* `footnoteLabel` (`string`, default: `'Footnotes'`)\n — label to use for the footnotes section (affects screen readers)\n* `footnoteLabelProperties`\n ([`Properties`][properties], default: `{className: ['sr-only']}`)\n — properties to use on the footnote label\n (note that `id: 'footnote-label'` is always added as footnote calls use it\n with `aria-describedby` to provide an accessible label)\n* `footnoteLabelTagName` (`string`, default: `h2`)\n — tag name to use for the footnote label\n* `handlers` ([`Handlers`][api-handlers], optional)\n — extra handlers for nodes\n* `passThrough` (`Array`, optional)\n — list of custom mdast node types to pass through (keep) in hast (note that\n the node itself is passed, but eventual children are transformed)\n* `unknownHandler` ([`Handler`][api-handler], optional)\n — handle all unknown nodes\n\n### `Raw`\n\nRaw string of HTML embedded into HTML AST (TypeScript type).\n\n###### Type\n\n```ts\nimport type {Data, Literal} from 'hast'\n\ninterface Raw extends Literal {\n type: 'raw'\n data?: RawData | undefined\n}\n\ninterface RawData extends Data {}\n```\n\n### `State`\n\nInfo passed around about the current state (TypeScript type).\n\n###### Fields\n\n* `all` (`(node: MdastNode) => Array`)\n — transform the children of an mdast parent to hast\n* `applyData` (`(from: MdastNode, to: Type) => Type | HastElement`)\n — honor the `data` of `from` and maybe generate an element instead of `to`\n* `definitionById` (`Map`)\n — definitions by their uppercased identifier\n* `footnoteById` (`Map`)\n — footnote definitions by their uppercased identifier\n* `footnoteCounts` (`Map`)\n — counts for how often the same footnote was called\n* `footnoteOrder` (`Array`)\n — identifiers of order when footnote calls first appear in tree order\n* `handlers` ([`Handlers`][api-handlers])\n — applied node handlers\n* `one` (`(node: MdastNode, parent: MdastNode | undefined) => HastNode | Array | undefined`)\n — transform an mdast node to hast\n* `options` ([`Options`][api-options])\n — configuration\n* `patch` (`(from: MdastNode, to: HastNode) => undefined`)\n* `wrap` (`(nodes: Array, loose?: boolean) => Array`)\n — wrap `nodes` with line endings between each node, adds initial/final line\n endings when `loose`\n\n## Examples\n\n### Example: supporting HTML in markdown naïvely\n\nIf you completely trust authors (or plugins) and want to allow them to HTML *in*\nmarkdown, and the last utility has an `allowDangerousHtml` option as well (such\nas `hast-util-to-html`) you can pass `allowDangerousHtml` to this utility\n(`mdast-util-to-hast`):\n\n```js\nimport {fromMarkdown} from 'mdast-util-from-markdown'\nimport {toHast} from 'mdast-util-to-hast'\nimport {toHtml} from 'hast-util-to-html'\n\nconst markdown = 'It works! ![]()
'\nconst mdast = fromMarkdown(markdown)\nconst hast = toHast(mdast, {allowDangerousHtml: true})\nconst html = toHtml(hast, {allowDangerousHtml: true})\n\nconsole.log(html)\n```\n\n…now running `node example.js` yields:\n\n```html\n![]()
'\nconst mdast = fromMarkdown(markdown)\nconst hast = raw(toHast(mdast, {allowDangerousHtml: true}))\nconst safeHast = sanitize(hast)\nconst html = toHtml(safeHast)\n\nconsole.log(html)\n```\n\n…now running `node example.js` yields:\n\n```html\n\n\n
\n\n> 👉 **Note**: GFM prescribes that the obsolete `align` attribute on `td` and\n> `th` elements is used.\n> To use `style` attributes instead of obsolete features, combine this utility\n> with [`@mapbox/hast-util-table-cell-style`][hast-util-table-cell-style].\n\n> 🧑🏫 **Info**: this project is concerned with turning one syntax tree into\n> another.\n> It does not deal with markdown syntax or HTML syntax.\n> The preceding examples are illustrative rather than authoritative or\n> exhaustive.\n\n### Fields on nodes\n\nA frequent problem arises when having to turn one syntax tree into another.\nAs the original tree (in this case, mdast for markdown) is in some cases\nlimited compared to the destination (in this case, hast for HTML) tree,\nis it possible to provide more info in the original to define what the\nresult will be in the destination?\nThis is possible by defining data on mdast nodes, which this utility will read\nas instructions on what hast nodes to create.\n\nAn example is math, which is a nonstandard markdown extension, that this utility\ndoesn’t understand.\nTo solve this, `mdast-util-math` defines instructions on mdast nodes that this\nplugin does understand because they define a certain hast structure.\n\nThe following fields can be used:\n\n* `node.data.hName` — define the element’s tag name\n* `node.data.hProperties` — define extra properties to use\n* `node.data.hChildren` — define hast children to use\n\n###### `hName`\n\n`node.data.hName` sets the tag name of an element.\nThe following [mdast][]:\n\n```js\n{\n type: 'strong',\n data: {hName: 'b'},\n children: [{type: 'text', value: 'Alpha'}]\n}\n```\n\n…yields ([hast][]):\n\n```js\n{\n type: 'element',\n tagName: 'b',\n properties: {},\n children: [{type: 'text', value: 'Alpha'}]\n}\n```\n\n###### `hProperties`\n\n`node.data.hProperties` sets the properties of an element.\nThe following [mdast][]:\n\n```js\n{\n type: 'image',\n src: 'circle.svg',\n alt: 'Big red circle on a black background',\n data: {hProperties: {className: ['responsive']}}\n}\n```\n\n…yields ([hast][]):\n\n```js\n{\n type: 'element',\n tagName: 'img',\n properties: {\n src: 'circle.svg',\n alt: 'Big red circle on a black background',\n className: ['responsive']\n },\n children: []\n}\n```\n\n###### `hChildren`\n\n`node.data.hChildren` sets the children of an element.\nThe following [mdast][]:\n\n```js\n{\n type: 'code',\n lang: 'js',\n data: {\n hChildren: [\n {\n type: 'element',\n tagName: 'span',\n properties: {className: ['hljs-meta']},\n children: [{type: 'text', value: '\"use strict\"'}]\n },\n {type: 'text', value: ';'}\n ]\n },\n value: '\"use strict\";'\n}\n```\n\n…yields ([hast][]):\n\n```js\n{\n type: 'element',\n tagName: 'pre',\n properties: {},\n children: [{\n type: 'element',\n tagName: 'code',\n properties: {className: ['language-js']},\n children: [\n {\n type: 'element',\n tagName: 'span',\n properties: {className: ['hljs-meta']},\n children: [{type: 'text', value: '\"use strict\"'}]\n },\n {type: 'text', value: ';'}\n ]\n }]\n}\n```\n\n> 👉 **Note**: the `pre` and `language-js` class are normal `mdast-util-to-hast`\n> functionality.\n\n## CSS\n\nAssuming you know how to use (semantic) HTML and CSS, then it should generally\nbe straightforward to style the HTML produced by this plugin.\nWith CSS, you can get creative and style the results as you please.\n\nSome semistandard features, notably GFMs tasklists and footnotes, generate HTML\nthat be unintuitive, as it matches exactly what GitHub produces for their\nwebsite.\nThere is a project, [`sindresorhus/github-markdown-css`][github-markdown-css],\nthat exposes the stylesheet that GitHub uses for rendered markdown, which might\neither be inspirational for more complex features, or can be used as-is to\nexactly match how GitHub styles rendered markdown.\n\nThe following CSS is needed to make footnotes look a bit like GitHub:\n\n```css\n/* Style the footnotes section. */\n.footnotes {\n font-size: smaller;\n color: #8b949e;\n border-top: 1px solid #30363d;\n}\n\n/* Hide the section label for visual users. */\n.sr-only {\n position: absolute;\n width: 1px;\n height: 1px;\n padding: 0;\n overflow: hidden;\n clip: rect(0, 0, 0, 0);\n word-wrap: normal;\n border: 0;\n}\n\n/* Place `[` and `]` around footnote calls. */\n[data-footnote-ref]::before {\n content: '[';\n}\n\n[data-footnote-ref]::after {\n content: ']';\n}\n```\n\n## Syntax tree\n\nThe following interfaces are added to **[hast][]** by this utility.\n\n### Nodes\n\n#### `Raw`\n\n```idl\ninterface Raw <: Literal {\n type: 'raw'\n}\n```\n\n**Raw** (**[Literal][dfn-literal]**) represents a string if raw HTML inside\nhast.\nRaw nodes are typically ignored but are handled by\n[`hast-util-to-html`][hast-util-to-html] and [`hast-util-raw`][hast-util-raw].\n\n## Types\n\nThis package is fully typed with [TypeScript][].\nIt exports the\n[`FootnoteBackContentTemplate`][api-footnote-back-content-template],\n[`FootnoteBackLabelTemplate`][api-footnote-back-label-template],\n[`Handler`][api-handler],\n[`Handlers`][api-handlers],\n[`Options`][api-options],\n[`Raw`][api-raw], and\n[`State`][api-state] types.\n\nIt also registers the `Raw` node type with `@types/hast`.\nIf you’re working with the syntax tree (and you pass\n`allowDangerousHtml: true`), make sure to import this utility somewhere in your\ntypes, as that registers the new node type in the tree.\n\n```js\n/**\n * @import {Root} from 'hast'\n * @import {} from 'mdast-util-to-hast'\n */\n\nimport {visit} from 'unist-util-visit'\n\n/** @type {Root} */\nconst tree = { /* … */ }\n\nvisit(tree, function (node) {\n // `node` can now be `raw`.\n})\n```\n\nFinally, it also registers the `hChildren`, `hName`, and `hProperties` fields\non `Data` of `@types/mdast`.\nIf you’re working with the syntax tree, make sure to import this utility\nsomewhere in your types, as that registers the data fields in the tree.\n\n```js\n/**\n * @import {Root} from 'hast'\n * @import {} from 'mdast-util-to-hast'\n */\n\nimport {visit} from 'unist-util-visit'\n\n/** @type {Root} */\nconst tree = { /* … */ }\n\nconsole.log(tree.data?.hName) // Types as `string | undefined`.\n```\n\n## Compatibility\n\nProjects maintained by the unified collective are compatible with maintained\nversions of Node.js.\n\nWhen we cut a new major release, we drop support for unmaintained versions of\nNode.\nThis means we try to keep the current release line, `mdast-util-to-hast@^13`,\ncompatible with Node.js 16.\n\n## Security\n\nUse of `mdast-util-to-hast` can open you up to a\n[cross-site scripting (XSS)][xss] attack.\nEmbedded hast properties (`hName`, `hProperties`, `hChildren`), custom handlers,\nand the `allowDangerousHtml` option all provide openings.\n\nThe following example shows how a script is injected where a benign code block\nis expected with embedded hast properties:\n\n```js\nconst code = {type: 'code', value: 'alert(1)'}\n\ncode.data = {hName: 'script'}\n```\n\nYields:\n\n```html\n\n```\n\nThe following example shows how an image is changed to fail loading and\ntherefore run code in a browser.\n\n```js\nconst image = {type: 'image', url: 'existing.png'}\n\nimage.data = {hProperties: {src: 'missing', onError: 'alert(2)'}}\n```\n\nYields:\n\n```html\n![](\"missing\")
\n```\n\nThe following example shows the default handling of embedded HTML:\n\n```markdown\n# Hello\n\n\n```\n\nYields:\n\n```html\n
It works!
It works!
Bonjour1
\nFootnotes
\n- \n
- \n
Monde! ↩
\n \n
Bonjour1
\n-Footnotes
\n+Notes de bas de page
\n \n| mdast node | \nmarkdown example | \nhast node | \nhtml example | \n|
|---|---|---|---|---|
| \n\n[`blockquote`](https://github.com/syntax-tree/mdast#blockquote)\n\n | \n\n\n```markdown\n> A greater than…\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`blockquote`)\n\n | \n\n\n```html\n\n\n```\n\n | \n|
| \n\n[`break`](https://github.com/syntax-tree/mdast#break)\n\n | \n\n\n```markdown\nA backslash\\\nbefore a line break…\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`br`)\n\n | \n\n\n```html\n A backslash | \n|
| \n\n[`code`](https://github.com/syntax-tree/mdast#code)\n\n | \n\n\n````markdown\n```js\nbacktick.fences('for blocks')\n```\n````\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`pre` and `code`)\n\n | \n\n\n```html\n | \n|
| \n\n[`delete`](https://github.com/syntax-tree/mdast#delete) (GFM)\n\n | \n\n\n```markdown\nTwo ~~tildes~~ for delete.\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`del`)\n\n | \n\n\n```html\n Two | \n|
| \n\n[`emphasis`](https://github.com/syntax-tree/mdast#emphasis)\n\n | \n\n\n```markdown\nSome *asterisks* for emphasis.\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`em`)\n\n | \n\n\n```html\n Some asterisks for emphasis. \n```\n\n | \n|
| \n\n[`footnoteReference`](https://github.com/syntax-tree/mdast#footnotereference),\n[`footnoteDefinition`](https://github.com/syntax-tree/mdast#footnotedefinition)\n(GFM)\n\n | \n\n\n```markdown\nWith a [^caret].\n\n[^caret]: Stuff\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`section`, `sup`, `a`)\n\n | \n\n\n```html\n With a 1. …\n```\n\n | \n|
| \n\n[`heading`](https://github.com/syntax-tree/mdast#heading)\n\n | \n\n\n```markdown\n# One number sign…\n###### Six number signs…\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`h1`…`h6`)\n\n | \n\n\n```html\nOne number sign…\nSix number signs…\n```\n\n | \n|
| \n\n[`html`](https://github.com/syntax-tree/mdast#html)\n\n | \n\n\n```html\nCMD+S\n```\n\n | \n\n\nNothing (default), `raw` (when `allowDangerousHtml: true`)\n\n | \n\n\nn/a\n\n | \n|
| \n\n[`image`](https://github.com/syntax-tree/mdast#image)\n\n | \n\n\n```markdown\n![Alt text](/logo.png \"title\")\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`img`)\n\n | \n\n\n```html\n
| \n|
| \n\n[`imageReference`](https://github.com/syntax-tree/mdast#imagereference),\n[`definition`](https://github.com/syntax-tree/mdast#definition)\n\n | \n\n\n```markdown\n![Alt text][logo]\n\n[logo]: /logo.png \"title\"\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`img`)\n\n | \n\n\n```html\n
| \n|
| \n\n[`inlineCode`](https://github.com/syntax-tree/mdast#inlinecode)\n\n | \n\n\n```markdown\nSome `backticks` for inline code.\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`code`)\n\n | \n\n\n```html\n Some | \n|
| \n\n[`link`](https://github.com/syntax-tree/mdast#link)\n\n | \n\n\n```markdown\n[Example](https://example.com \"title\")\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`a`)\n\n | \n\n\n```html\n\n```\n\n | \n|
| \n\n[`linkReference`](https://github.com/syntax-tree/mdast#linkreference),\n[`definition`](https://github.com/syntax-tree/mdast#definition)\n\n | \n\n\n```markdown\n[Example][]\n\n[example]: https://example.com \"title\"\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`a`)\n\n | \n\n\n```html\n\n```\n\n | \n|
| \n\n[`list`](https://github.com/syntax-tree/mdast#list),\n[`listItem`](https://github.com/syntax-tree/mdast#listitem)\n\n | \n\n\n```markdown\n* asterisks for unordered items\n\n1. decimals and a dot for ordered items\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`li` and `ol` or `ul`)\n\n | \n\n\n```html\n
| \n|
| \n\n[`paragraph`](https://github.com/syntax-tree/mdast#paragraph)\n\n | \n\n\n```markdown\nJust some text…\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`p`)\n\n | \n\n\n```html\n Just some text… \n```\n\n | \n|
| \n\n[`root`](https://github.com/syntax-tree/mdast#root)\n\n | \n\n\n```markdown\nAnything!\n```\n\n | \n\n\n[`root`](https://github.com/syntax-tree/hast#root)\n\n | \n\n\n```html\n Anything! \n```\n\n | \n|
| \n\n[`strong`](https://github.com/syntax-tree/mdast#strong)\n\n | \n\n\n```markdown\nTwo **asterisks** for strong.\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`strong`)\n\n | \n\n\n```html\n Two asterisks for strong. \n```\n\n | \n|
| \n\n[`text`](https://github.com/syntax-tree/mdast#text)\n\n | \n\n\n```markdown\nAnything!\n```\n\n | \n\n\n[`text`](https://github.com/syntax-tree/hast#text)\n\n | \n\n\n```html\n Anything! \n```\n\n | \n|
| \n\n[`table`](https://github.com/syntax-tree/mdast#table),\n[`tableRow`](https://github.com/syntax-tree/mdast#tablerow),\n[`tableCell`](https://github.com/syntax-tree/mdast#tablecell)\n\n | \n\n\n```markdown\n| Pipes |\n| ----- |\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`table`, `thead`,\n`tbody`, `tr`, `td`, `th`)\n\n | \n\n\n```html\n
| \n|
| \n\n[`thematicBreak`](https://github.com/syntax-tree/mdast#thematicbreak)\n\n | \n\n\n```markdown\nThree asterisks for a thematic break:\n\n***\n```\n\n | \n\n\n[`element`](https://github.com/syntax-tree/hast#element) (`hr`)\n\n | \n\n\n```html\n Three asterisks for a thematic break: \n\n```\n\n | \n|
| \n\n`toml` (frontmatter)\n\n | \n\n\n```markdown\n+++\nfenced = true\n+++\n```\n\n | \n\n\nNothing\n\n | \n\n\nn/a\n\n | \n|
| \n\n[`yaml`](https://github.com/syntax-tree/mdast#yaml) (frontmatter)\n\n | \n\n\n```markdown\n---\nfenced: yes\n---\n```\n\n | \n\n\nNothing\n\n | \n\n\nn/a\n\n | \n
![\"Alt](\"/logo.png\" "\\"title\\""){kind=logo}