markdown-it/README.md

# markdown-it

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> Markdown parser done right. Fast and easy to extend.

__[Live demo](https://markdown-it.github.io)__

- Follows the __[CommonMark spec](http://spec.commonmark.org/)__ + adds syntax extensions & sugar (URL autolinking, typographer).
- Configurable syntax! You can add new rules and even replace existing ones.
- High speed.
- [Safe](https://github.com/markdown-it/markdown-it/tree/master/docs/security.md) by default.
- Community-written __[plugins](https://www.npmjs.org/browse/keyword/markdown-it-plugin)__ and [other packages](https://www.npmjs.org/browse/keyword/markdown-it) on npm.

__Table of content__

- [Install](#install)
- [Usage examples](#usage-examples)
- [API](#api)
- [Syntax extensions](#syntax-extensions)
- [Benchmark](#benchmark)
- [Authors](#authors)
- [References / Thanks](#references--thanks)
- [License](#license)

## Install

**node.js** & **bower**:

```bash
npm install markdown-it --save
bower install markdown-it --save
```

**browser (CDN):**

- [jsDeliver CDN](http://www.jsdelivr.com/#!markdown-it "jsDelivr CDN")
- [cdnjs.com CDN](https://cdnjs.com/libraries/markdown-it "cdnjs.com")


## Usage examples

See also:

- __[API documentation](https://markdown-it.github.io/markdown-it/)__ - for more
  info and examples.
- [Development info](https://github.com/markdown-it/markdown-it/tree/master/docs) -
  for plugins writers.


### Simple

```js
// 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:

```js
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](https://markdown-it.github.io/markdown-it/#MarkdownIt.new) for more details.

```js
// 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
  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 externaly.
  // If result starts with <pre... internal wrapper is skipped.
  highlight: function (/*str, lang*/) { return ''; }
});
```

### Plugins load

```js
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:

```js
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(lang, str).value;
      } catch (__) {}
    }

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

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

```js
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(lang, str, true).value +
               '</code></pre>';
      } catch (__) {}
    }

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

### Linkify

`linkify: true` uses [linkify-it](https://github.com/markdown-it/linkify-it). To
configure linkify-it, access the linkify instance through `md.linkify`:

```js
md.linkify.tlds('.py', false);  // disables .py as top level domain
```


## API

__[API documentation](https://markdown-it.github.io/markdown-it/)__

If you are going to write plugins - take a look at
[Development info](https://github.com/markdown-it/markdown-it/tree/master/docs).


## Syntax extensions

Embedded (enabled by default):

- [Tables](https://help.github.com/articles/github-flavored-markdown/#tables) (GFM)
- [Strikethrough](https://help.github.com/articles/github-flavored-markdown/#strikethrough) (GFM)

Via plugins:

- [subscript](https://github.com/markdown-it/markdown-it-sub)
- [superscript](https://github.com/markdown-it/markdown-it-sup)
- [footnote](https://github.com/markdown-it/markdown-it-footnote)
- [definition list](https://github.com/markdown-it/markdown-it-deflist)
- [abbreviation](https://github.com/markdown-it/markdown-it-abbr)
- [emoji](https://github.com/markdown-it/markdown-it-emoji)
- [custom container](https://github.com/markdown-it/markdown-it-container)
- [insert](https://github.com/markdown-it/markdown-it-ins)
- [mark](https://github.com/markdown-it/markdown-it-mark)
- ... and [others](https://www.npmjs.org/browse/keyword/markdown-it-plugin)


### Manage rules

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

```js
// 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,
});
```


## Benchmark

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

```bash
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](https://github.com/markdown-it/markdown-it/blob/master/benchmark/implementations/current-commonmark/index.js)
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.


## Authors

- Alex Kocharin [github/rlidwka](https://github.com/rlidwka)
- Vitaly Puzrin [github/puzrin](https://github.com/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](https://github.com/jgm) 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](https://github.com/digitalmoksha/motion-markdown-it) - Ruby/RubyMotion


## License

[MIT](https://github.com/markdown-it/markdown-it/blob/master/LICENSE)