Escape regular expressions about jsesc

[mathiasbynens]

That would still not work when escapeEverything: true is used, as it would escape characters with special meaning, such as [] etc. We could make it so that the regex.source is stringEscaped with escapeEverything: false at all times, though.

[mathiasbynens]

Currently escaping regular expressions works as expected, as long as the original regular expression wasn’t constructed using escape sequences.

E.g. when regex is /\xA9/, regex.source is '\\xA9'. Running that through stringEscape() adds another layer of escaping, which leads to incorrect results.

We could do something like https://github.com/mathiasbynens/mothereff.in/blob/880f773b51200fc901d9159ad5fa369d440b6cae/js-escapes/eff.js#L50-L57 but perhaps it’s just not worth it.