An îles module that injects a remark plugin to provide syntax highlighting for MDX documents:

• 💎 uses PrismJS supporting a wide variety of programming languages

• 🔦 highlight specific lines ({3}, {7-13}, or {16,23-27,40})

• 🔢 display line numbers (showLineNumbers)

• 🚀 faster than @mapbox/rehype-prism, remark-prism and rehype-prism-plus

Usage 🚀

Add the module to iles.config.ts:

// iles.config.ts
import { defineConfig } from 'iles'

export default defineConfig({
  modules: [
    '@islands/prism',
  ],
})

Then, you can highlight lines or display line numbers in code blocks:

```js {6} showLineNumbers
// iles.config.ts
import { defineConfig } from 'iles'

export default defineConfig({
  modules: [
    '@islands/prism',
  ],
})
```

Configuration ⚙️

You can also import the module directly to get autocompletion when providing options:

// iles.config.ts
import { defineConfig } from 'iles'

import prism from '@islands/prism'

export default defineConfig({
  modules: [
    prism({
      aliases: { zsh: 'bash' },
      showLineNumbers: true,
    }),
  ],
})

When showLineNumbers is enabled globally, you can use hideLineNumbers to opt-out in a specific code block.

Styling 🎨

Each code block will be transformed to HTML with the following structure:

<div class="language-js" data-lang="js">
  <pre class="line-highlight">...</pre>
  <pre class="language-ts"><code>...</code></pre>
  <pre class="line-numbers">...</pre>
</div>

You can use the following styles to ensure everything lines up as expected:

div[class*='language-'] {
  position: relative;
  /* background, font-size, line-height */
}

div[class*='language-'] pre {
  /* padding */
}

pre[class*='language-'] {
  position: relative; /* position it to allow text selection */
  overflow: auto;
}

pre.line-highlight,
pre.line-numbers {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  margin: 0;
  width: 100%;
  user-select: none;
  overflow: hidden;
}

.line-highlight > .highlighted {
  background: rgba(0,0,0,0.1);
}

div[class*='language-'].line-numbers-mode {
  --gutter-width: 3.5rem;
  padding-left: calc(var(--gutter-width) + 1rem);
}

pre.line-numbers {
  border-right: 1px solid rgba(0,0,0,0.1);
  text-align: center;
  width: var(--gutter-width);
}

If you wish to display the language, you can use the value of the data-lang attribute by using the attr CSS function:

div[class*='language-'] {
  position: relative;
}

div[class*='language-']::before {
  content: attr(data-lang);
  color: #888;
  font-size: 0.8rem;
  position: absolute;
  right: 1em;
  top: 0.6em;
}