Auto Sass

Package for the Atom IDE that takes a Sass file on each save and automatically compiles, lints, prefixes, and saves the resulting CSS code.

This plugin was something I developed rather quickly and primarily with my own use in mind. I wouldn't expect that others would find it any more useful than the myriad Sass compiler packages already out there.

Motivation to publicize and provide this brief explainer is mostly to make it easier for me when I eventually have to come back to debug something. Perhaps others might find it useful as well though.

Notable Changes

v1.2.0

Added busy-signal integration
Fixed the previously non-responsive manual auto-sass:compile command

v1.1.1

Major speedup on start; from max of 1200ms down to < 5ms (on my machine)
Big reduction in unnecessary function calls

Features

Uses latest Dart Sass Node API
Lints and fixes compiled CSS with Stylelint using nearest .stylintrc config available
Runs Autoprefixer on compiled CSS
Deduplicates multiple selector blocks with postcss-combine-duplicated-selectors
- (yet to test if this has unintended results, off by default)
Does all the above before actually saving the output to file
Makes it easier and quicker to live test a site as you build

Usage

Install

Search for auto-sass and install from Atom's in-app settings UI

Or, if you prefer via CLI:

apm install auto-sass

Settings

In the package settings UI, you can turn on/off any of the three additional post-compilation tasks:

linting
prefixing
deduplicating

There are also some module-specific configs exposed as well, including some of Dart Sass' common options (e.g. output style, source map) and fallback/override options related to Browserlist and Stylelint.

Output path

You can set the default file name and path for the output CSS relative to its source Sass file. Use $1 as a stand in for the original file name (without extension).

By default, the output path location is set to ../$1.css, or in other words:

assets/css/src/main.scss
               ↓
assets/css/main.css

File-specific output

You can also override the output path on a per-file basis by following a compile: or out: keyword in a first-line comment of that Sass file, as shown below:

css/src/home.scss:

// compile: ../$1/styles.css

$sassy-var: 16px;
@include my-mixin();
.
.

On save this Sass file would get compiled and saved to:

css/home/styles.css

Partial files

Auto Sass doesn't compile partial Sass files of course—that's the whole point of the partials feature after all, however, it's quite handy to have certain downstream Sass files (i.e. those @importing or @useing that partial file) recompiled automatically when the partial is saved.

You can tell Auto Sass to do this by adding a first-line comment similarly as described above to your partial file, but instead using a downstream:, main:, or link: keyword followed by a comma-separated list of Sass file paths—relative to current file, as before—that you would like to have auto-compiled whenever the current file is saved:

css/src/main.scss:

@import "modules/_partial.scss";
.
.

css/src/modules/_partial.scss:

// main: ../main.scss

$red: #FF0000;
$etc: "...";
.
.

For these couple of files, if we save _partial.scss, it will go and compile main.scss as if you had just saved that file.

Notes

With just those two basic first-line comment commands, we can chain up the compilation of files in pretty complex ways, though for simplicity's sake, I'm sure you'd rarely want to have a chain involving more than 3-5 files, max.

Also, while I described the "downstream" compiling feature to be for partials... you could make use of this on any other Sass file. The use case in _partials is just most apparent.

Misc

Not sure what the trend/long-term outlook is with Atom, I've found a lot of widely used packages remain unmaintained with stale deps... weird bugs I thought were due to this package ended up being problems with other linters and such.

I hope future me doesn't pull his hair out trying to squash a bug that's out of his control.

Why does Stylelint seemingly only do caching if exec directly via CLI and ignore cache: true opt via node API?

Twitter: @nlydv

License

This project is licensed under the terms of the MIT License.
Full license text is available in the LICENSE.txt file.