fencen

Safe and simple utilities for wrapping code in Markdown-style fences.

Usage

import fencen, {blockFences, inlineFences, pickFence} from 'fencen'

fencen('hello')
// ```
// hello
// ```

const fence = pickFence('hello')
fence.opener() // '```\n'
fence.closer() // '\n```'

fencen('hello ` world', {inline: true})
// `` hello ` world ``

fencen('const value = 1', {inline: true, language: 'ts'})
// <code language="ts">const value = 1</code>

pickFence returns a Fence with opener() and closer() renderers. Block Markdown fences render language after the opener. Inline output with a language uses the XML <code language="…"> fence because Markdown inline-code fences have no language syntax. XML attribute values are escaped.

Trimming

trim accepts a boolean or object:

fencen(input, {
  trim: {
    vertical: true,
    lines: true,
    indentation: true,
  },
})

trim: true is equivalent to:

{
  vertical: true,
  lines: false,
  indentation: false,
}

vertical removes surrounding blank lines, lines trims trailing whitespace from each line and indentation removes shared leading indentation. trim defaults to true.

Fence candidates

blockFences and inlineFences are static arrays. pickFence checks them in order and throws a RangeError if none is safe.

Block candidates are:

~~~
~~~~
~~~~~
~~~~~~

````````
<code>
```

Inline candidates are:

```text
`
``
```
````
<code>
```

Multi-backtick inline fences include a trailing space in the opener and a leading space in the closer. The single-backtick fence and `<code>` fallback are unspaced.