markdown-it

What is markdown-it?

The markdown-it npm package is a Markdown parser that can convert Markdown text into HTML. It is highly extensible and supports various plugins to enhance its functionality. It is commonly used to render user-generated content in web applications, documentation tools, and content management systems.

What are markdown-it's main functionalities?

Basic Markdown Parsing

This feature allows you to convert basic Markdown text into HTML. The code sample demonstrates how to create a new instance of MarkdownIt and use it to render a simple Markdown string.

const MarkdownIt = require('markdown-it');
const md = new MarkdownIt();
const result = md.render('# Markdown-it rulezz!');

HTML Output Customization

Markdown-it allows customization of the HTML output through options. The code sample shows how to enable HTML tags in source, automatically convert URLs to links, and use typographic replacements.

const MarkdownIt = require('markdown-it');
const md = new MarkdownIt({
  html: true,
  linkify: true,
  typographer: true
});

Syntax Extensions with Plugins

Markdown-it supports plugins to extend its syntax. The code sample demonstrates how to add emoji support to the Markdown parser using the markdown-it-emoji plugin.

const MarkdownIt = require('markdown-it');
const emojiPlugin = require('markdown-it-emoji');
const md = new MarkdownIt();
md.use(emojiPlugin);
const result = md.render('Hello :smile:');

Linkify

The linkify feature automatically detects URLs in the text and converts them into clickable links. The code sample shows how to enable this feature in the MarkdownIt instance.

const MarkdownIt = require('markdown-it');
const md = new MarkdownIt({
  linkify: true
});
const result = md.render('Visit https://www.example.com');

Other packages similar to markdown-it

marked

Marked is a fast Markdown parser and compiler built for speed. It is less extensible than markdown-it but is known for its performance and being a low-level compiler.

remarkable

Remarkable is another Markdown parser that claims to be very fast and efficient. It offers similar extensibility to markdown-it with a plugin system and is often used for its speed and comprehensive Markdown support.

showdown

Showdown is a JavaScript Markdown to HTML converter that can run both on the server and in the browser. It is often chosen for its client-side capabilities and extensibility with extensions.

README

markdown-it

Markdown parser done right. Fast and easy to extend.

Live demo

• Follows the CommonMark spec + adds syntax extensions & sugar (URL autolinking, typographer).
• Configurable syntax! You can add new rules and even replace existing ones.
• High speed.
• Safe by default.
• Community-written plugins and other packages on npm.

Table of content

• Install
• Usage examples
  • Simple
  • Init with presets and options
  • Plugins load
  • Syntax highlighting
  • Linkify
• API
• Syntax extensions
  • Manage rules
• Benchmark
• markdown-it for enterprise
• Authors
• References / Thanks

Install

node.js:

npm install markdown-it --save

browser (CDN):

• jsDeliver CDN
• cdnjs.com CDN

Usage examples

See also:

• API documentation - for more info and examples.
• Development info - for plugins writers.

Simple

// node.js, "classic" way:
var MarkdownIt = require('markdown-it'),
    md = new MarkdownIt();
var result = md.render('# markdown-it rulezz!');

// node.js, the same, but with sugar:
var md = require('markdown-it')();
var result = md.render('# markdown-it rulezz!');

// browser without AMD, added to "window" on script load
// Note, there is no dash in "markdownit".
var md = window.markdownit();
var result = md.render('# markdown-it rulezz!');

Single line rendering, without paragraph wrap:

var md = require('markdown-it')();
var result = md.renderInline('__markdown-it__ rulezz!');

Init with presets and options

(*) presets define combinations of active rules and options. Can be "commonmark", "zero" or "default" (if skipped). See API docs for more details.

// commonmark mode
var md = require('markdown-it')('commonmark');

// default mode
var md = require('markdown-it')();

// enable everything
var md = require('markdown-it')({
  html: true,
  linkify: true,
  typographer: true
});

// full options list (defaults)
var md = require('markdown-it')({
  html:         false,        // Enable HTML tags in source
  xhtmlOut:     false,        // Use '/' to close single tags (<br />).
                              // This is only for full CommonMark compatibility.
  breaks:       false,        // Convert '\n' in paragraphs into <br>
  langPrefix:   'language-',  // CSS language prefix for fenced blocks. Can be
                              // useful for external highlighters.
  linkify:      false,        // Autoconvert URL-like text to links

  // Enable some language-neutral replacement + quotes beautification
  // For the full list of replacements, see https://github.com/markdown-it/markdown-it/blob/master/lib/rules_core/replacements.js
  typographer:  false,

  // Double + single quotes replacement pairs, when typographer enabled,
  // and smartquotes on. Could be either a String or an Array.
  //
  // For example, you can use '«»„“' for Russian, '„“‚‘' for German,
  // and ['«\xA0', '\xA0»', '‹\xA0', '\xA0›'] for French (including nbsp).
  quotes: '“”‘’',

  // Highlighter function. Should return escaped HTML,
  // or '' if the source string is not changed and should be escaped externally.
  // If result starts with <pre... internal wrapper is skipped.
  highlight: function (/*str, lang*/) { return ''; }
});

Plugins load

var md = require('markdown-it')()
            .use(plugin1)
            .use(plugin2, opts, ...)
            .use(plugin3);

Syntax highlighting

Apply syntax highlighting to fenced code blocks with the highlight option:

var hljs = require('highlight.js'); // https://highlightjs.org/

// Actual default values
var md = require('markdown-it')({
  highlight: function (str, lang) {
    if (lang && hljs.getLanguage(lang)) {
      try {
        return hljs.highlight(str, { language: lang }).value;
      } catch (__) {}
    }

    return ''; // use external default escaping
  }
});

Or with full wrapper override (if you need assign class to <pre>):

var hljs = require('highlight.js'); // https://highlightjs.org/

// Actual default values
var md = require('markdown-it')({
  highlight: function (str, lang) {
    if (lang && hljs.getLanguage(lang)) {
      try {
        return '<pre class="hljs"><code>' +
               hljs.highlight(str, { language: lang, ignoreIllegals: true }).value +
               '</code></pre>';
      } catch (__) {}
    }

    return '<pre class="hljs"><code>' + md.utils.escapeHtml(str) + '</code></pre>';
  }
});

Linkify

linkify: true uses linkify-it. To configure linkify-it, access the linkify instance through md.linkify:

md.linkify.set({ fuzzyEmail: false });  // disables converting email to link

API

API documentation

If you are going to write plugins - take a look at Development info.

Syntax extensions

Embedded (enabled by default):

• Tables (GFM)
• Strikethrough (GFM)

Via plugins:

• subscript
• superscript
• footnote
• definition list
• abbreviation
• emoji
• custom container
• insert
• mark
• ... and others

Manage rules

By default all rules are enabled, but can be restricted by options. On plugin load all its rules are enabled automatically.

// Activate/deactivate rules, with curring
var md = require('markdown-it')()
            .disable([ 'link', 'image' ])
            .enable([ 'link' ])
            .enable('image');

// Enable everything
md = require('markdown-it')({
  html: true,
  linkify: true,
  typographer: true,
});

You can find all rules in sources: parser_core.js, parser_block, parser_inline.

Benchmark

Here is the result of readme parse at MB Pro Retina 2013 (2.4 GHz):

make benchmark-deps
benchmark/benchmark.js readme

Selected samples: (1 of 28)
 > README

Sample: README.md (7774 bytes)
 > commonmark-reference x 1,222 ops/sec ±0.96% (97 runs sampled)
 > current x 743 ops/sec ±0.84% (97 runs sampled)
 > current-commonmark x 1,568 ops/sec ±0.84% (98 runs sampled)
 > marked x 1,587 ops/sec ±4.31% (93 runs sampled)

Note. CommonMark version runs with simplified link normalizers for more "honest" compare. Difference is ~ 1.5x.

As you can see, markdown-it doesn't pay with speed for it's flexibility. Slowdown of "full" version caused by additional features not available in other implementations.

markdown-it for enterprise

Available as part of the Tidelift Subscription.

The maintainers of markdown-it and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.

Authors

• Alex Kocharin github/rlidwka
• Vitaly Puzrin github/puzrin

markdown-it is the result of the decision of the authors who contributed to 99% of the Remarkable code to move to a project with the same authorship but new leadership (Vitaly and Alex). It's not a fork.

References / Thanks

Big thanks to John MacFarlane for his work on the CommonMark spec and reference implementations. His work saved us a lot of time during this project's development.

Related Links:

• https://github.com/jgm/CommonMark - reference CommonMark implementations in C & JS, also contains latest spec & online demo.
• http://talk.commonmark.org - CommonMark forum, good place to collaborate developers' efforts.

Ports

• motion-markdown-it - Ruby/RubyMotion
• markdown-it-py- Python

Changelog

[12.3.2] - 2022-01-08

Security

• Fix possible ReDOS in newline rule. Thanks to @MakeNowJust.