remarkable

What is remarkable?

The 'remarkable' npm package is a powerful markdown parser that allows you to convert markdown text into HTML. It is highly configurable and supports a wide range of markdown features, making it suitable for various use cases such as rendering markdown content on websites, converting markdown files to HTML, and more.

What are remarkable's main functionalities?

Basic Markdown to HTML Conversion

This feature allows you to convert basic markdown text into HTML. The code sample demonstrates how to convert a markdown heading into HTML.

const Remarkable = require('remarkable');
const md = new Remarkable();
const html = md.render('# Hello, world!');
console.log(html);

Custom Syntax Highlighting

This feature allows you to add custom syntax highlighting to code blocks in your markdown. The code sample demonstrates how to use the 'highlight.js' library to highlight JavaScript code within a markdown code block.

const Remarkable = require('remarkable');
const hljs = require('highlight.js');
const md = new Remarkable({
  highlight: function (str, lang) {
    if (lang && hljs.getLanguage(lang)) {
      try {
        return hljs.highlight(lang, str).value;
      } catch (__) {}
    }
    return ''; // use external default escaping
  }
});
const html = md.render('```js\nconsole.log("Hello, world!");\n```');
console.log(html);

Customizing Markdown Rendering

This feature allows you to customize various aspects of markdown rendering. The code sample demonstrates how to enable HTML tags, convert newlines to <br> tags, and automatically convert URLs to links.

const Remarkable = require('remarkable');
const md = new Remarkable({
  html: true, // Enable HTML tags in source
  xhtmlOut: true, // Use '/' to close single tags (<br />)
  breaks: true, // Convert '\n' in paragraphs into <br>
  langPrefix: 'language-', // CSS language prefix for fenced blocks
  linkify: true, // Autoconvert URL-like text to links
  typographer: true // Enable smartypants and other sweet transforms
});
const html = md.render('# Hello, world!\nThis is a [link](http://example.com).');
console.log(html);

Other packages similar to remarkable

marked

The 'marked' package is another popular markdown parser that is known for its speed and flexibility. It offers similar functionality to 'remarkable' but is often preferred for its performance and ease of use.

markdown-it

The 'markdown-it' package is a highly extensible markdown parser that supports plugins and a wide range of markdown features. It is similar to 'remarkable' in terms of configurability and feature set, but it also offers additional plugins for extended functionality.

showdown

The 'showdown' package is a markdown to HTML converter that is known for its simplicity and ease of use. It provides a straightforward API for converting markdown to HTML and is often used in projects where simplicity is a priority.

README

remarkable

Markdown parser done right. Fast and easy to extend.

Live demo

• Supports the CommonMark spec + syntax extensions + sugar (URL autolinking, typographer).
• Configurable syntax! You can add new rules and even replace existing ones.
• High speed!
• Community plugins on npm.

Install

node.js:

npm install remarkable --save

bower:

bower install remarkable --save

browser (CDN):

• jsDeliver CDN
• cdnjs

Usage

var Remarkable = require('remarkable');
var md = new Remarkable();

console.log(md.render('# Remarkable rulezz!'));
// => <h1>Remarkable rulezz!</h1>

If installed globally with npm:

cat myfile.md | remarkable
remarkable --file myfile.md

# get options
remarkable -h

Documentation

See the docs directory for documentation on the following topics:

• parser
• parsing_block
• parsing_core
• parsing_inline
• plugins
• renderer

Options

By default, remarkable is configured to be similar to GFM, but with HTML disabled. This is easy to change if you prefer different settings.

There are two ways to define options.

constructor

Define options in the constructor:

// Actual default values
var md = new Remarkable({
  html:         false,        // Enable HTML tags in source
  xhtmlOut:     false,        // Use '/' to close single tags (<br />)
  breaks:       false,        // Convert '\n' in paragraphs into <br>
  langPrefix:   'language-',  // CSS language prefix for fenced blocks
  linkify:      false,        // Autoconvert URL-like text to links

  // Enable some language-neutral replacement + quotes beautification
  typographer:  false,

  // Double + single quotes replacement pairs, when typographer enabled,
  // and smartquotes on. Set doubles to '«»' for Russian, '„“' for German.
  quotes: '“”‘’',

  // Highlighter function. Should return escaped HTML,
  // or '' if the source string is not changed
  highlight: function (/*str, lang*/) { return ''; }
});

console.log(md.render('# Remarkable rulezz!'));
// => <h1>Remarkable rulezz!</h1>

.set

Or define options via the .set() method:

var Remarkable = require('remarkable');
var md = new Remarkable();

md.set({
  html: true,
  breaks: true
});

Note: To achieve the best possible performance, don't modify a Remarkable instance on the fly. If you need multiple configurations, create multiple instances and initialize each with a configuration that is ideal for that instance.

Presets

Remarkable offers some "presets" as a convenience to quickly enable/disable active syntax rules and options for common use cases.

commonmark

Enable strict CommonMark mode with the commonmark preset:

var Remarkable = require('remarkable');
var md = new Remarkable('commonmark');

full

Enable all available rules (but still with default options, if not set):

var Remarkable = require('remarkable');
var md = new Remarkable('full');

// Or with options:
var md = new Remarkable('full', {
  html: true,
  linkify: true,
  typographer: true
});

Syntax highlighting

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

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

// Actual default values
var md = new Remarkable({
  highlight: function (str, lang) {
    if (lang && hljs.getLanguage(lang)) {
      try {
        return hljs.highlight(lang, str).value;
      } catch (err) {}
    }

    try {
      return hljs.highlightAuto(str).value;
    } catch (err) {}

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

Syntax extensions

Enabled by default:

• Footnotes
• Tables (GFM)
• <del> (GFM strikethrough) - ~~deleted text~~

Disabled by default:

• <sup> - 19^th^
• <sub> - H~2~O
• abbreviations
• <ins> - ++inserted text++ (experimental)
• <mark> - ==marked text== (experimental)

HEADS UP!: Experimental extensions can be changed later for something like Critic Markup, but you will still be able to use old-style rules via external plugins if you prefer.

Manage rules

var md = new Remarkable();
md.inline.ruler.enable([ 'ins', 'mark' ]);
md.block.ruler.disable([ 'table', 'footnote' ]);

// Enable everything
md = new Remarkable('full', {
  html: true,
  linkify: true,
  typographer: true,
});

//
// Manually enable rules, disabled by default:
//
var md = new Remarkable();
md.core.ruler.enable([
  'abbr'
]);
md.block.ruler.enable([
  'footnote',
  'deflist'
]);
md.inline.ruler.enable([
  'footnote_inline',
  'ins',
  'mark',
  'sub',
  'sup'
]);

Typographer

Although full-weight typographical replacements are language specific, remarkable provides coverage for the most common and universal use cases:

var Remarkable = require('remarkable');
var md = new Remarkable({
  typographer: true,
  quotes: '“”‘’'
});

// Disable rules at all:
md.core.ruler.disable([ 'replacements', 'smartquotes' ]);

// Actual default replacements:
//
// '' → ‘’
// "" → “”. Set '«»' for Russian, '„“' for German, empty to disable
// (c) (C) → ©
// (tm) (TM) → ™
// (r) (R) → ®
// +- → ±
// (p) (P) -> §
// ... → … (also ?.... → ?.., !.... → !..)
// ???????? → ???, !!!!! → !!!, `,,` → `,`
// -- → –, --- → —
//

Of course, you can also add your own rules or replace the defaults with something more advanced or specific to your language.

Plugins

Easily load plugins with the .use() method:

var md = new Remarkable();

md.use(plugin1)
  .use(plugin2, opts)
  .use(plugin3);

Please refer to the plugin documentation to create your own plugins.

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:

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

Development / Modification

Parser consists of several responsibility chains filled with rules. You can reconfigure any of them as you wish. Renderer also can be modified and extended. See source code to understand details. Pay attention to these properties:

Remarkable.core
Remarkable.core.ruler
Remarkable.block
Remarkable.block.ruler
Remarkable.inline
Remarkable.inline.ruler
Remarkable.renderer
Remarkable.renderer.rules

Benchmark

Here is result of CommonMark spec parse at Core i5 2.4 GHz (i5-4258U):

$ benchmark/benchmark.js spec
Selected samples: (1 of 27)
 > spec

Sample: spec.txt (110610 bytes)
 > commonmark-reference x 40.42 ops/sec ±4.07% (51 runs sampled)
 > current x 74.99 ops/sec ±4.69% (67 runs sampled)
 > current-commonmark x 93.76 ops/sec ±1.23% (79 runs sampled)
 > marked-0.3.2 x 22.92 ops/sec ±0.79% (41 runs sampled)

As you can see, remarkable doesn't pay with speed for its flexibility. Because it's written in monomorphic style and uses JIT inline caches effectively.

Authors

• Jon Schlinkert github/jonschlinkert
• Alex Kocharin github/rlidwka
• Vitaly Puzrin github/puzrin

License

MIT