sass

A pure JavaScript implementation of Sass.

  • sass

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A pure JavaScript implementation of Sasssass. Sass makes CSS fun again.
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This package is a distribution of Dart Sass, compiled to pure JavaScript with no native code or external dependencies. It provides a command-line sass executable and a Node.js API.

Usage

You can install Sass globally using npm install -g sass which will provide access to the sass executable. You can also add it to your project using npm install --save-dev sass. This provides the executable as well as a library:
const sass = require('sass');

const result = sass.compile(scssFilename);

// OR

// Note that `compileAsync()` is substantially slower than `compile()`.
const result = await sass.compileAsync(scssFilename);

See the Sass websitejs api for full API documentation.

Legacy API

Dart Sass also supports an 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 of outputStyle are
supported.
  • Dart Sass doesn't support the precision option. Dart Sass defaults to a
sufficiently high precision for all existing browsers, and making this customizable would make the code substantially less efficient.
  • Dart Sass doesn't support the sourceComments option. Source maps are the
recommended way of locating the origin of generated selectors.

See Also

  • Dart Sass, from which this package is compiled, can be used either as a
stand-alone executable or as a Dart library. Running Dart Sass on the Dart VM is substantially faster than running the pure JavaScript version, so this may be appropriate for performance-sensitive applications. The Dart API is also (currently) more user-friendly than the JavaScript API. See the Dart Sass READMEUsing Dart Sass for details on how to use it.
of Sass. Node Sass supports the same API as this package and is also faster (although it's usually a little slower than Dart Sass). However, it requires a native library which may be difficult to install, and it's generally slower to add features and fix bugs.

Behavioral Differences from Ruby Sass

There are a few intentional behavioral differences between Dart Sass and Ruby Sass. These are generally places where Ruby Sass has an undesired behavior, and it's substantially easier to implement the correct behavior than it would be to implement compatible behavior. These should all have tracking bugs against Ruby Sass to update the reference behavior.
  1. @extend only accepts simple selectors, as does the second argument of
`selector-extend()`. See [issue 1599][].
  1. Subject selectors are not supported. See issue 1126.

  1. Pseudo selector arguments are parsed as <declaration-value>s rather than
having a more limited custom parsing. See [issue 2120][].
  1. The numeric precision is set to 10. See issue 1122.

  1. The indented syntax parser is more flexible: it doesn't require consistent
indentation across the whole document. See [issue 2176][].
  1. Colors do not support channel-by-channel arithmetic. See issue 2144.

  1. Unitless numbers aren't == to unit numbers with the same value. In
addition, map keys follow the same logic as `==`-equality. See
[issue 1496][].
  1. rgba() and hsla() alpha values with percentage units are interpreted as
percentages. Other units are forbidden. See [issue 1525][].
  1. Too many variable arguments passed to a function is an error. See
[issue 1408][].
  1. Allow @extend to reach outside a media query if there's an identical
`@extend` defined outside that query. This isn't tracked explicitly, because
it'll be irrelevant when [issue 1050][] is fixed.
  1. Some selector pseudos containing placeholder selectors will be compiled
where they wouldn't be in Ruby Sass. This better matches the semantics of
the selectors in question, and is more efficient. See [issue 2228][].
  1. The old-style :property value syntax is not supported in the indented
syntax. See [issue 2245][].
  1. The reference combinator is not supported. See issue 303.

  1. Universal selector unification is symmetrical. See issue 2247.

  1. @extend doesn't produce an error if it matches but fails to unify. See
[issue 2250][].
  1. Dart Sass currently only supports UTF-8 documents. We'd like to support
more, but Dart currently doesn't support them. See [dart-lang/sdk#11744][],
for example.
Disclaimer: this is not an official Google product.