How does this library handle transliteration of non-ASCII characters?

Question

RepoPilot · Accepted Answer

The sindresorhus/slugify library handles transliteration of non-ASCII characters through a configurable option that leverages an external dependency.

## Default Behavior

By default, the library **transliterates Unicode characters to ASCII**. It uses the `@sindresorhus/transliterate` package [package.json:L26-L55] to convert non-ASCII characters to their ASCII equivalents. For example:

```js
slugify('Déjà Vu');
//=> 'deja-vu'
```

The accented characters `é` and `à` are converted to their ASCII counterparts `e` and `a`.

## Transliteration Option

You can disable transliteration by setting `transliterate: false` in the options [index.d.ts:L176-L205]:

```js
slugify('Déjà Vu', {transliterate: false});
//=> 'déjà-vu'
```

When disabled, non-ASCII characters are preserved in the slug instead of being converted. This can improve performance when transliteration isn't needed [readme.md:L226-L255].

## Pattern Building

In the implementation, when transliteration is disabled, the library adjusts its regex pattern to preserve Unicode letters and numbers. The `buildPatternSlug` function [index.js:L26-L55] adds `\p{L}\p{N}` to the negation set pattern when `transliterate === false`, allowing Unicode letter and number characters to be kept in the output.

Additionally, you can use the `locale` option to specify language-specific transliteration rules [index.d.ts:L151-L180], which is passed through to the `@sindresorhus/transliterate` package.

FOLLOW_UPS:
- What does the `locale` option control?
- How are custom character replacements processed?
- What regex flags are used for pattern matching?