[tag:bug]

I searched around, but couldn't find any previous posts referencing RegEx. 
RegEx is stated to be [currently supported][1], but it *is not* in the [list of languages supported][2] by highlight.js (it *was* supported by Prettify). 

There are some weird effects when highlighting complex expressions, eg. from [this answer][3]:

```regex
(?:[a-z0-9!#$%&'*+\/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+\/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9]))\.){3}(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])
```

It sometimes italicizes the characters between asterisks `*`, and other times fails to highlight character lists inside square brackets `[]`.

If it's not supported by highlight.js, where is this highlighting scheme even coming from? Is RegEx included in the FAQ list by mistake<sup>1</sup>? I notice that the default highlighter for the [tag:regex] tag on SO is `lang-default` rather than `lang-regex`.

---

<sup>1</sup> - It looks like it was added back into the list in the FAQ post on Sept. 28 ([Rev. 100][4]).


 [1]: https://meta.stackexchange.com/a/184109/776523
 [2]: https://github.com/highlightjs/highlight.js/blob/master/SUPPORTED_LANGUAGES.md
 [3]: https://stackoverflow.com/a/201378/11047824
 [4]: https://meta.stackexchange.com/revisions/184109/100
 [5]: https://meta.stackexchange.com/revisions/184109/11