small commonmark compliant markdown parser with positional info and concrete tokens
Micromark is a powerful, low-level Markdown parser and compiler. It allows for parsing Markdown content into abstract syntax trees (ASTs), manipulating those trees, and then compiling them back into Markdown or HTML. It's designed for flexibility, extensibility, and adherence to the CommonMark specification, making it suitable for a wide range of applications where Markdown processing is required.
Parsing Markdown to HTML
This feature allows you to convert Markdown text into HTML. The code sample demonstrates how to parse a simple Markdown heading into its HTML equivalent.
const micromark = require('micromark');
const html = micromark('# Hello World');
console.log(html);Extensibility with Syntax Extensions
Micromark can be extended with additional syntax features not covered by the CommonMark specification. This example shows how to use the GitHub Flavored Markdown (GFM) extension to parse text with GFM-specific features.
const micromark = require('micromark');
const gfm = require('micromark-extension-gfm');
const html = micromark('Hello, world!', {extensions: [gfm()]});
console.log(html);Custom HTML Renderers
This feature allows for custom HTML rendering of Markdown elements. The code sample demonstrates how to customize the rendering of images by adding a custom CSS class to the <img> tag.
const micromark = require('micromark');
const html = micromark('', {
htmlExtensions: [{
enter: {image: (node) => `<img src="${node.url}" alt="${node.alt}" class="custom-class">`}
}]
});
console.log(html);Marked is a fast Markdown parser and compiler built for speed. It is simpler and less customizable than micromark but offers a good balance between speed and extensibility for many common use cases.
Remark is part of the unified collective and provides a powerful Markdown processor powered by plugins. It focuses on the manipulation of Markdown and ASTs, similar to micromark, but with a higher-level API and a broader ecosystem of plugins for extended functionality.
Showdown is a JavaScript Markdown to HTML converter, which can be used both on the client side and server side. It is designed to be easy to use and extend, similar to micromark, but with a focus on simplicity and ease of integration into existing projects.
The smallest CommonMark compliant markdown parser with positional info and concrete tokens.
micromark is a long awaited markdown parser.
It uses a state machine to parse the entirety of markdown into tokens.
It’s the smallest 100% CommonMark compliant markdown parser in JavaScript.
It’ll replace the internals of remark-parse, the most
popular markdown parser (remarkjs/remark#536).
Its interface is optimized to compile to HTML, but its parts can be used
to generate syntax trees (mdast-util-from-markdown) or
compile to other output formats too.
It’s in open beta: up next are integration in remark, CMSM, and CSTs.
unifiedjs.comnpm:
npm install micromark
Typical use (buffering):
var micromark = require('micromark')
console.log(micromark('## Hello, *world*!'))
Yields:
<h2>Hello, <em>world</em>!</h2>
Extensions (in this case micromark-extension-gfm):
var micromark = require('micromark')
var gfmSyntax = require('micromark-extension-gfm')
var gfmHtml = require('micromark-extension-gfm/html')
var doc = '* [x] contact@example.com ~~strikethrough~~'
var result = micromark(doc, {
extensions: [gfmSyntax()],
htmlExtensions: [gfmHtml]
})
console.log(result)
Yields:
<ul>
<li><input checked="" disabled="" type="checkbox"> <a href="mailto:contact@example.com">contact@example.com</a> <del>strikethrough</del></li>
</ul>
Streaming interface:
var fs = require('fs')
var micromarkStream = require('micromark/stream')
fs.createReadStream('example.md')
.on('error', handleError)
.pipe(micromarkStream())
.pipe(process.stdout)
function handleError(err) {
// Handle your error here!
throw err
}
Note that there are also as of yet undocumented APIs to use the individual parts of micromark and to make extensions.
micromark(doc[, encoding][, options])Compile markdown to HTML.
docMarkdown to parse (string or Buffer)
encodingCharacter encoding to understand doc as when it’s a
Buffer (string, default: 'utf8').
options.defaultLineEndingValue to use for line endings not in doc (string, default: first line
ending or '\n').
Generally, micromark copies line endings ('\r', '\n', '\r\n') in the
markdown document over to the compiled HTML.
In some cases, such as > a, CommonMark requires that extra line endings are
added: <blockquote>\n<p>a</p>\n</blockquote>.
options.allowDangerousHtmlWhether to allow embedded HTML (boolean, default: false).
options.allowDangerousProtocolWhether to allow potentially dangerous protocols in links and images (boolean,
default: false).
URLs relative to the current protocol are always allowed (such as, image.jpg).
For links, the allowed protocols are http, https, irc, ircs, mailto,
and xmpp.
For images, the allowed protocols are http and https.
options.extensionsArray of syntax extensions (Array.<SyntaxExtension>,
default: []).
options.htmlExtensionsArray of HTML extensions (Array.<HtmlExtension>, default:
[]).
string — Compiled HTML.
micromarkStream(options?)Streaming interface of micromark.
Compiles markdown to HTML.
options are the same as the buffering API above.
Available at require('micromark/stream').
Note that some of the work to parse markdown can be done streaming, but in the
end it requires buffering.
micromark does not handle errors for you, so you must handle errors on whatever
streams you pipe into it.
As markdown does not know errors, micromark itself does not emit errors.
There are two types of extensions for micromark:
SyntaxExtension and HtmlExtension.
They can be passed in extensions or
htmlExtensions, respectively.
SyntaxExtensionA syntax extension is an object whose fields are the names of tokenizers:
content (a block of, well, content: definitions and paragraphs), document
(containers such as block quotes and lists), flow (block constructs such as
ATX and setext headings, HTML, indented and fenced code, thematic breaks),
string (things that work in a few places such as destinations, fenced code
info, etc: character escapes and -references), or text (rich inline text:
autolinks, character escapes and -references, code, hard breaks, HTML, images,
links, emphasis, strong).
The values at such objects are character codes, mapping to constructs. The built in constructs are an extension. See it and the existing extensions for inspiration.
HtmlExtensionAn HTML extension is an object whose fields are either enter or exit
(reflecting whether a token is entered or exited).
The values at such objects are names of tokens mapping to handlers.
See the existing extensions for inspiration.
micromark/micromark-extension-footnote
— support footnotesmicromark/micromark-extension-frontmatter
— support frontmatter (YAML, TOML, etc)micromark/micromark-extension-gfm
— support GFM (GitHub Flavored Markdown)micromark/micromark-extension-gfm-autolink-literal
— support GFM autolink literalsmicromark/micromark-extension-gfm-strikethrough
— support GFM strikethroughmicromark/micromark-extension-gfm-table
— support GFM tablesmicromark/micromark-extension-gfm-tagfilter
— support GFM tagfiltermicromark/micromark-extension-gfm-task-list-item
— support GFM tasklistsmicromark/micromark-extension-math
— support mathA higher level project, mdast-util-from-markdown, can give
you an AST.
var fromMarkdown = require('mdast-util-from-markdown')
var result = fromMarkdown('## Hello, *world*!')
console.log(result.children[0])
Yields:
{
type: 'heading',
depth: 2,
children: [
{type: 'text', value: 'Hello, ', position: [Object]},
{type: 'emphasis', children: [Array], position: [Object]},
{type: 'text', value: '!', position: [Object]}
],
position: {
start: {line: 1, column: 1, offset: 0},
end: {line: 1, column: 19, offset: 18}
}
}
Another level up is remark, which provides a nice interface and hundreds of plugins.
The first definition of “Markdown” gave several examples of how it worked,
showing input Markdown and output HTML, and came with a reference implementation
(known as Markdown.pl).
When new implementations followed, they mostly followed the first definition,
but deviated from the first implementation, and added extensions, thus making
the format a family of formats.
Some years later, an attempt was made to standardize the differences between implementations, by specifying how several edge cases should be handled, through more input and output examples. This attempt is known as CommonMark, and many implementations now work towards some degree of CommonMark compliancy. Still, CommonMark describes what the output in HTML should be given some input, which leaves many edge cases up for debate, and does not answer what should happen for other output formats.
micromark passes all tests from CommonMark and has many more tests to match the CommonMark reference parsers. Finally, it comes with CMSM, which describes how to parse markup, instead of documenting input and output examples.
micromark is tested with the ~650 CommonMark tests and more than 1000 extra tests confirmed with other markdown parsers. These tests reach all branches in the code, thus this project has 100% coverage. Finally, we use fuzz testing to ensure micromark is stable, reliable, and secure.
micromark is really small. A ton of time went into making sure it minifies well, by the way code is written but also through custom build scripts to pre-evaluate certain expressions. Furthermore, care went into making it compress well with GZip and Brotli.
Normally, you’ll use the pre-evaluated version of micromark, which is published
in the dist/ folder and has entries in the root.
While developing or debugging, you can switch to use the source, which is
published in the lib/ folder, and comes instrumented with assertions and debug
messages.
To see debug messages, run your script with a DEBUG env variable, such as with
DEBUG="micromark" node script.js.
There are many other markdown parsers out there, and maybe they’re better suited
to your use case!
Here is a short comparison of a couple of ’em in JavaScript.
Note that this list is made by the folks who make micromark and remark, so
there is some bias.
micromark is the lowest you can go: it gives tremendous power, such as access to
all tokens with positional info, at the cost of being hard to get into.
It’s super small, pretty fast, and has 100% CommonMark compliance.
It has syntax extensions, such as supporting 100% GFM compliance (with
micromark-extension-gfm), but they’re rather complex to write.
It’s the newest parser on the block.
If you’re looking for fine grained control, use micromark.
remark is the most popular markdown parser.
It’s built on top of micromark and boasts syntax trees.
For an analogy, it’s like if Babel, ESLint, and more, were one project.
It supports the syntax extensions that micromark has (so it’s 100% CM compliant
and can be 100% GFM compliant), but most of the work is done in plugins that
transform or inspect the tree.
Transforming the tree is relatively easy: it’s a JSON object that can be
manipulated directly.
remark is stable, widely used, and extremely powerful for handling complex data.
If you’re looking to inspect or transform lots of content, use remark.
marked is the oldest markdown parser on the block. It’s been around for ages, is battle tested, small, popular, and has a bunch of extensions, but doesn’t match CommonMark or GFM, and is unsafe by default.
If you have markdown you trust and want to turn it into HTML without a fuss, use marked.
markdown-it is a good, stable, and essentially CommonMark compliant markdown parser, with (optional) support for some GFM features as well. It’s used a lot as a direct dependency in packages, but is rather big. It shines at syntax extensions, where you want to support not just markdown, but your (company’s) version of markdown.
If you’re in Node and have CommonMark-compliant (or funky) markdown and want to turn it into HTML, use markdown-it.
There are lots of other markdown parsers!
Some say they’re small, or fast, or that they’re CommonMark compliant — but
that’s not always true.
This list is not supposed to be exhaustive.
This list of markdown parsers is a snapshot in time of why (not) to use
(alternatives to) micromark: they’re all good choices, depending on what your
goals are.
The open beta of micromark starts at version 2.0.0 (there was a different
package published on npm as micromark before).
micromark will adhere to semver at 3.0.0.
Use tilde ranges for now: "micromark": "~2.9.2".
It’s safe to compile markdown to HTML if it does not include embedded HTML nor
uses dangerous protocols in links (such as javascript: or data:).
micromark is safe by default if embedded HTML or dangerous protocols are used
too, as it encodes or drops them.
Turning on the allowDangerousHtml or allowDangerousProtocol options for
user-provided markdown opens you up to cross-site scripting (XSS)
attacks.
For more information on markdown sanitation, see
improper-markup-sanitization.md by @chalker.
See security.md in micromark/.github for how to
submit a security report.
See contributing.md in micromark/.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, organisation, or community you agree to abide by its terms.
Support this effort and give back by sponsoring on OpenCollective!
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small commonmark compliant markdown parser with positional info and concrete tokens
The npm package micromark receives a total of 4,018,166 weekly downloads. As such, micromark popularity was classified as popular.
We found that micromark demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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