Awesome
Embedded Sass Host
This package is an alternative to the sass
package. It supports the same JS
API as sass
and is maintained by the same team, but where the sass
package
is pure JavaScript, sass-embedded
is instead a JavaScript wrapper around a
native Dart executable. This means sass-embedded
will generally be much faster
especially for large Sass compilations, but it can only be installed on the
platforms that Dart supports: Windows, Mac OS, and Linux.
Despite being different packages, both sass
and sass-embedded
are considered
"Dart Sass" since they have the same underlying implementation. Since the first
stable release of the sass-embedded
package, both packages are released at the
same time and share the same version number.
Usage
This package provides the same JavaScript API as the sass
package, and can be
used as a drop-in replacement:
const sass = require('sass-embedded');
const result = sass.compile(scssFilename);
// OR
const result = await sass.compileAsync(scssFilename);
Unlike the sass
package, the asynchronous API in sass-embedded
will
generally be faster than the synchronous API since the Sass compilation logic is
happening in a different process.
See the Sass website for full API documentation.
Legacy API
The sass-embedded
package also supports the older JavaScript API that's fully
compatible with Node Sass (with a few exceptions listed below), with support
for both the render()
and renderSync()
functions. This API is considered
deprecated and will be removed in Dart Sass 2.0.0, so it should be avoided in
new projects.
Sass's support for the legacy JavaScript API has the following limitations:
-
Only the
"expanded"
and"compressed"
values ofoutputStyle
are supported. -
The
sass-embedded
package doesn't support theprecision
option. Dart Sass defaults to a sufficiently high precision for all existing browsers, and making this customizable would make the code substantially less efficient. -
The
sass-embedded
package doesn't support the [sourceComments
] option. Source maps are the recommended way of locating the origin of generated selectors. -
The
sass-embedded
package doesn't support theindentWidth
,indentType
, orlinefeed
options. It implements the legacy API as a wrapper around the new API, and the new API has dropped support for these options.
How Does It Work?
The sass-embedded
runs the Dart Sass embedded compiler as a separate
executable and uses the Embedded Sass Protocol to communicate with it over its
stdin and stdout streams. This protocol is designed to make it possible not only
to start a Sass compilation, but to control aspects of it that are exposed by an
API. This includes defining custom importers, functions, and loggers, all of
which are invoked by messages from the embedded compiler back to the host.
Although this sort of two-way communication with an embedded process is
inherently asynchronous in Node.js, this package supports the synchronous
compile()
API using a custom synchronous message-passing library that's
implemented with the Atomics.wait()
primitive. We hope to release this
library as a stand-alone package at some point in the future.
Disclaimer: this is not an official Google product.