# markdown-it-highlightjs [![npm version](https://img.shields.io/npm/v/markdown-it-highlightjs.svg?style=flat-square)](https://www.npmjs.org/package/markdown-it-highlightjs)

> Preset to use [highlight.js] with [markdown-it].

[highlight.js]: https://highlightjs.org/
[markdown-it]: https://github.com/markdown-it/markdown-it

## Usage

```js
const md = require('markdown-it')()
  .use(require('markdown-it-highlightjs'), opts)
```

This will process all code blocks with highlight.js to add `span`
elements around grammatical keywords with specific classes, that can
then be syled with CSS. You can find a list of preset highlighting
styles [here](https://github.com/highlightjs/highlight.js/tree/main/src/styles).

The `opts` object can contain:

| Name              | Type    | Description                                                                                                               | Default                   |
|-------------------|---------|---------------------------------------------------------------------------------------------------------------------------|---------------------------|
| `auto`            | boolean | Whether to automatically detect language if not specified.                                                                | `true`                    |
| `code`            | boolean | Whether to add the `hljs` class to raw code blocks (not fenced blocks).                                                   | `true`                    |
| `register`        | object  | Register other languages which are not included in the standard pack.                                                     | `null`                    |
| `registerAliases` | object  | Register aliases to languages which are included in the standard pack.                                                    | `null`                    |
| `inline`          | boolean | Whether to highlight inline code.                                                                                         | `false`                   |
| `hljs`            | object  | Provide the instance of [highlight.js] to use for highlighting                                                            | `require('highlight.js')` |
| `ignoreIllegals`  | boolean | Forces highlighting to finish even in case of detecting illegal syntax for the language instead of throwing an exception. | `true`                    |

## Register languages

```js
const md = require('markdown-it')()
  .use(require('markdown-it-highlightjs'), {
    register: {
      cypher: require('highlightjs-cypher')
    }
  })
```

## Register language aliases

```js
const md = require('markdown-it')()
  .use(require('markdown-it-highlightjs'), {
    registerAliases: {
      js: ['jquery', 'jqueryui']
    }
  })
```

## Inline code highlighting

You can enable inline code highlighting by setting `inline` to true:

```js
const md = require('markdown-it')()
  .use(require('markdown-it-highlightjs'), { inline: true })
```

You can specify the language for inline code using
[Pandoc syntax](https://pandoc.org/MANUAL.html#extension-inline_code_attributes):

```markdown
`x=4`{.js}
```

Or [kramdown IAL syntax](https://kramdown.gettalong.org/syntax.html#inline-attribute-lists):

```markdown
`x=4`{:.js}
```

If you do not specify a language, then highlight.js will attempt to
guess the language if `auto` is true (which it is by default).

### Usage with markdown-it-attrs

If you use markdown-it-attrs, make sure to include it *after*
markdown-it-highlightjs if you want inline code highlighting to work:

```js
const md = require('markdown-it')()
  .use(require('markdown-it-highlightjs'), { inline: true })
  .use(require('markdown-it-attrs'))
```

## Provide the [highlight.js] instance

You can specify the `hljs` option to override the default [highlight.js]
instance with your own:

```js
const hljs = require('highlight.js/lib/core')

hljs.registerLanguage(
  'javascript',
  require('highlight.js/lib/languages/javascript')
)

const md = require('markdown-it')()
  .use(require('markdown-it-highlightjs'), { hljs })
```

## Core plugin

You may import the core `markdown-it-highlightjs` plugin directly,
without any default options. You must specify an instance of
[highlight.js] for the `hljs` option.

```js
const hljs = require('highlight.js/lib/core')

const md = require('markdown-it')()
  .use(require('markdown-it-highlightjs/core'), { hljs })
```