Parcel: Move to dart-sass instead of node-sass

[pablomayobre]

🙋 Feature Request

Since late march dart-sass reached the stable release 1.0.0, marking the start of the deprecation of ruby-sass (not libsass though).

Although node-sass is based on libsass and will continue to be updated with the latest patch and fixes, it will take more time for this features to land while dart-sass will receive them immediately and has the benefit of compiling to pure JS without the need of native modules.

Dart-sass is now at version 1.5.1 (as of 8/6/2018) and in nice shape to be used in production. NPM Link

🤔 Expected Behavior

Parcel should be able to detect the sass module instead of node-sass, and maybe fallback to it, if needed, though it may be a good idea to drop it altogether and look forward to #1253

😯 Current Behavior

Parcel incorrectly detects sass and asks for node-sass instead, failing to compile .sass/.scss files

💁 Possible Solution

Luckily sass is API compatible with node-sass so it should be as easy as changing the 2 occurrences of node-sass to sass at package.json line 90 and SASSAsset.js line 16

[DeMoorJasper]

Dart sass is slower and would require the dart runtime right?

[pablomayobre]

Citing Dart Sass performance

Dart Sass on Node lags behind, particularly when many extends are in use. It's still faster than it was last measurement, but it would probably pay dividends to do some JS-specific benchmarking and optimization to try to bring the speed closer to that of the Dart VM. The majority of our users run Dart Sass through JS, so while it's good that they have a path to better performance with the same semantics, improving the baseline performance is important.

So yeah it's slower, but it's pure JS. I also saw mentions of pure JavaScript version here

Also the compiled Dart Sass standalone (which doesn't require the Dart VM) seems to be on par to libsass and may be faster for some test cases

PS: It may be a good idea to ask someone on the Sass team to clarify this stuff

[DeMoorJasper]

Pure JS isn’t necessarily better, the major issues we currently have with sass are unrelated with it being in C++.
Idk if it’s worth the tradeoff would indeed be usefull to have someone from sass shim a light on this issue

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[sindresorhus]

@DeMoorJasper You should at least let people be able to choose dart-sass? It has additional benefits like not requiring a native addon.

There are also a myriad of issues with using node-sass with Parcel:

• https://github.com/parcel-bundler/parcel/issues/1331 (closed but still an issue for many)
• https://github.com/parcel-bundler/parcel/issues/1836

// @nex3

[DeMoorJasper]

@sindresorhus I thought we fixed the freezing issue, that’s why I thought this issue was pretty unnecessary, but now that someone has reported it again I’m pretty sure it’s a good idea to support dart-sass, still unfortunate that they don’t have a solid sass-js or something.

I’ll probably open up a pr for this later today (or link a plugin)

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