---
title: rehype-highlight-lines
---
Published as [@freesewing/rehype-highlight-lines][1], this package provides
a [Rehype](https://github.com/rehypejs/rehype)
plugin to format highlighted and struck-out lines in code blocks.
## Installation
```sh
npm install @freesewing/rehype-highlight-lines
```
## Usage
In NodeJS:
```js
import rehypeHighlightLines from @freesewing/rehype-highlight-lines
...
rehypePlugins: [
[
rehypeHighlightLines,
{
highlightClass: ['highlight-lines', 'border-l-4'],
strikeoutClass: [
'strikeout-lines',
'bg-orange-300',
'bg-opacity-5',
'border-l-4',
'opacity-80',
'line-through',
'decoration-orange-500',
],
},
],
],
```
### Example
```js
// These 3 lines will be highlighted:
// highlight-start
const a = 1
const b = 2
const c = 3
// highlight-end
const d = 4
// These 2 lines will be struck out:
// strikeout-start
const e = 5
const f = 6
// strikeout-end
```
## Configuration
| Property | Type | Default | Description |
|----------|------|---------|-------|
| commentTag | String | 'span' | Tag that identifies a comment. |
| commentClass | String | 'hljs-comment' | CSS class that identifies a comment.|
| openingCommentHighlight | String | 'highlight-start' | Comment text to start formatting lines as highlighted. |
| closingCommentHighlight | String | 'highlight-end' | Comment text to stop formatting lines as highlighted. |
| openingCommentStrikeout | String | 'strikeout-start' | Comment text to start formatting lines as struck-out. |
| closingCommentStrikeout | String | 'strikeout-end' | Comment text to stop formatting lines as struck-out. |
| highlightTag | String | 'section' | Tag to apply to the block of highlighted or struck-out lines. |
| highlightClass | Array|String | 'highlight-lines' | CSS classes to apply to highlighted lines. |
| strikeoutClass | Array|String | 'strikeout-lines' | CSS classes to apply to struck-out lines. |
| swallow | Boolean | `true` | Remove extra linebreaks before the start of highlighted/struck-out lines. |
[1]: https://www.npmjs.com/package/@freesewing/rehype-highlight-lines
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