remark-html

remark plugin to add support for serializing HTML.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • unified().use(remarkHtml[, options])
• Types
• Compatibility
• Security
• Related
• Contribute
• License

What is this?

This package is a unified (remark) plugin that compiles markdown to HTML.

unified is a project that transforms content with abstract syntax trees (ASTs). remark adds support for markdown to unified. rehype adds support for HTML to unified. mdast is the markdown AST that remark uses. hast is the HTML AST that rehype uses. This is a remark plugin that adds a compiler to compile mdast to hast and then to a string.

When should I use this?

This plugin is useful when you want to turn markdown into HTML. It’s a shortcut for .use(remarkRehype).use(rehypeStringify).

The reason that there are different ecosystems for markdown and HTML is that turning markdown into HTML is, while frequently needed, not the only purpose of markdown. Checking (linting) and formatting markdown are also common use cases for remark and markdown. There are several aspects of markdown that do not translate 1-to-1 to HTML. In some cases markdown contains more information than HTML: for example, there are several ways to add a link in markdown (as in, autolinks: <https://url>, resource links: [label](url), and reference links with definitions: [label][id] and [id]: url). In other cases HTML contains more information than markdown: there are many tags, which add new meaning (semantics), available in HTML that aren’t available in markdown. If there was just one AST, it would be quite hard to perform the tasks that several remark and rehype plugins currently do.

This plugin is useful when you want to quickly turn markdown into HTML. In most cases though, it’s recommended to use remark-rehype instead and finally use rehype-stringify to serialize HTML. The reason using both ecosystems instead of this plugin is recommended, is that there are many useful rehype plugins that you can then use. For example, you can minify HTML, format HTML, highlight code, add metadata, and a lot more.

Install

This package is ESM only. In Node.js (version 12.20+, 14.14+, or 16.0+), install with npm:

npm install remark-html

In Deno with esm.sh:

import remarkHtml from 'https://esm.sh/remark-html@15'

In browsers with esm.sh:

<script type="module">
  import remarkHtml from 'https://esm.sh/remark-html@15?bundle'
</script>

Use

Say we have the following file example.md:

# Hello & World

> A block quote.

* Some _emphasis_, **importance**, and `code`.

And our module example.js looks as follows:

import {read} from 'to-vfile'
import {unified} from 'unified'
import remarkParse from 'remark-parse'
import remarkHtml from 'remark-html'

main()

async function main() {
  const file = await unified()
    .use(remarkParse)
    .use(remarkHtml)
    .process(await read('example.md'))

  console.log(String(file))
}

Now running node example.js yields:

<h1>Hello &#x26; World</h1>
<blockquote>
<p>A block quote.</p>
</blockquote>
<ul>
<li>Some <em>emphasis</em>, <strong>importance</strong>, and <code>code</code>.</li>
</ul>

API

This package exports no identifiers. The default export is remarkHtml.

unified().use(remarkHtml[, options])

Add support for serializing HTML.

options

Configuration (optional). All options other than sanitize and handlers are passed to hast-util-to-html.

options.handlers

This option is a bit advanced as it requires knowledge of ASTs, so we defer to the documentation available in mdast-util-to-hast.

options.sanitize

How to sanitize the output (Object or boolean, default: true):

• false — output is not sanitized, dangerous raw HTML persists
• true — output is sanitized according to GitHub’s sanitation rules, dangerous raw HTML is dropped
• Object — schema that defines how to sanitize output with hast-util-sanitize, dangerous raw HTML is dropped

Types

This package is fully typed with TypeScript. It exports an Options type, which specifies the interface of the accepted options.

Compatibility

Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

This plugin works with unified version 6+ and remark version 7+.

Security

Use of remark-html is unsafe by default and opens you up to cross-site scripting (XSS) attacks. Pass sanitize: true to prevent attacks. Setting sanitize to anything else can be unsafe.

Related

• remark-rehype — turn markdown into HTML to support rehype
• rehype-sanitize — sanitize HTML

Contribute

See contributing.md in remarkjs/.github for ways to get started. See support.md for ways to get help.

This project has a code of conduct. By interacting with this repository, organization, or community you agree to abide by its terms.

License

MIT © Titus Wormer