feat(regexp): add escape function

[lionel-rowe]

Fixes #3330

Escaping is fairly conservative to account for context sensitivity and forward compatibility with the v flag — the only non-alphanumeric printable ASCIIS that aren't escaped are "'_, and of the characters that are escaped, almost half use the most conservative \x hex notation. That could be reduced a little (but not much) by ignoring characters in ClassSetReservedDoublePunctuator, which only need escaping if repeated adjacent to each other in a within a character class in a v-flagged regex.

[kt3k]

Thanks for the suggestion!

I think the directory name should be regexp/ instead of regex/ as JS has RegExp class, and also the API name should be regexpEscape (or regExpEscape?) instead of regexEscape. What do you think?

[lionel-rowe]

I think the directory name should be regexp/ instead of regex/ as JS has RegExp class, and also the API name should be regexpEscape (or regExpEscape?) instead of regexEscape. What do you think?

This is probably one of those "gif/jif" things that everyone has their own strong opinions about, but it seems like regex is the more common usage within the community at large by a significant margin (a Google search for "javascript regex" gives 597k results, whereas "javascript regexp" gives 175k; meanwhile on GitHub, regex gives 6,970 JS repository results, whereas regexp gives 2,063).

Still, this function would typically be used when interpolating/concatenating content into strings passed to the RegExp constructor, so that's something in favor of regexp. Also, grepping for regex gives results for both variants, whereas grepping for regexp only gives results for regexp.

I started writing this answer arguing in favor of regex, but I think I've convinced myself that regexp is the better option 😅 happy to change unless anyone has a more convincing argument for regex.

[iuioiua]

Still, this function would typically be used when interpolating/concatenating content into strings passed to the RegExp constructor, so that's something in favor of regexp. Also, grepping for regex gives results for both variants, whereas grepping for regexp only gives results for regexp.

+1 for regexp

[kt3k]

@lionel-rowe Thanks for updating to std/regexp!

I now wonder if we could make API name just escape instead regExpEscape. I think that's more aligned to the rest of deno_std. (For example, parse in std/yaml not yamlParse, format in fmt/bytes instead of formatBytes (or bytesFormat), etc

[lionel-rowe]

@lionel-rowe Thanks for updating to std/regexp!

I now wonder if we could make API name just escape instead regExpEscape. I think that's more aligned to the rest of deno_std. (For example, parse in std/yaml not yamlParse, format in fmt/bytes instead of formatBytes (or bytesFormat), etc

Done and done!

[kt3k]

LGTM 👍