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The sass npm package is a preprocessor scripting language that is interpreted or compiled into Cascading Style Sheets (CSS). It enables developers to use variables, nested rules, mixins, functions, and more, which can help in writing CSS in a more structured and maintainable way.
Variables
Variables allow you to store values that you can reuse throughout your stylesheet.
$primary-color: #333;
body {
color: $primary-color;
}
Nesting
Nesting enables you to nest your CSS selectors in a way that follows the same visual hierarchy of your HTML.
nav {
ul {
margin: 0;
padding: 0;
list-style: none;
}
li { display: inline-block; }
a {
display: block;
padding: 6px 12px;
text-decoration: none;
}
}
Partials and Import
Partials are Sass files named with a leading underscore. You can import these partials into other Sass files to modularize your CSS and help keep things easier to maintain.
// _reset.scss
html,
body,
ul,
ol {
margin: 0;
padding: 0;
}
// main.scss
@import 'reset';
body {
font-family: sans-serif;
}
Mixins
Mixins allow you to define styles that can be reused throughout your stylesheet.
@mixin border-radius($radius) {
-webkit-border-radius: $radius;
-moz-border-radius: $radius;
-ms-border-radius: $radius;
border-radius: $radius;
}
.box { @include border-radius(10px); }
Extend/Inheritance
Extend/Inheritance lets you share a set of CSS properties from one selector to another.
.message {
border: 1px solid #ccc;
padding: 10px;
color: #333;
}
.success {
@extend .message;
border-color: green;
}
Operators
Sass supports standard math operators like +, -, *, /, and %.
.container {
width: 100%;
}
.article {
width: 600px / 960px * 100%;
}
Less is a backward-compatible language extension for CSS. It provides similar features to Sass, such as variables, mixins, and nesting. However, Less uses JavaScript for compilation, whereas Sass was originally written in Ruby and now primarily uses a C implementation (Dart Sass).
Stylus is a preprocessor that offers a more flexible syntax than Sass and Less, with optional semicolons and braces. It also provides powerful features like variable interpolation and iteration. Stylus can be more terse and expressive in some cases but might have a steeper learning curve for those used to more traditional CSS syntax.
PostCSS is a tool for transforming CSS with JavaScript plugins. While it is not a preprocessor in the traditional sense, it can be used to achieve many of the same goals as Sass through its extensive plugin ecosystem. PostCSS is highly customizable and can be tailored to specific build processes and requirements.
A pure JavaScript implementation of Sass. 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.
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 website for full API documentation.
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.
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 README for details on how to use it.
Node Sass, which is a wrapper around LibSass, the C++ implementation 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.
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.
@extend
only accepts simple selectors, as does the second argument of
selector-extend()
. See issue 1599.
Subject selectors are not supported. See issue 1126.
Pseudo selector arguments are parsed as <declaration-value>
s rather than
having a more limited custom parsing. See issue 2120.
The numeric precision is set to 10. See issue 1122.
The indented syntax parser is more flexible: it doesn't require consistent indentation across the whole document. See issue 2176.
Colors do not support channel-by-channel arithmetic. See issue 2144.
Unitless numbers aren't ==
to unit numbers with the same value. In
addition, map keys follow the same logic as ==
-equality. See
issue 1496.
rgba()
and hsla()
alpha values with percentage units are interpreted as
percentages. Other units are forbidden. See issue 1525.
Too many variable arguments passed to a function is an error. See issue 1408.
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.
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.
The old-style :property value
syntax is not supported in the indented
syntax. See issue 2245.
The reference combinator is not supported. See issue 303.
Universal selector unification is symmetrical. See issue 2247.
@extend
doesn't produce an error if it matches but fails to unify. See
issue 2250.
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.
1.79.0
Breaking change: Passing a number with unit %
to the $alpha
parameter
of color.change()
, color.adjust()
, change-color()
, and adjust-color()
is now interpreted as a percentage, instead of ignoring the unit. For example,
color.change(red, $alpha: 50%)
now returns rgb(255 0 0 / 0.5)
.
Potentially breaking compatibility fix: Sass no longer rounds RGB channels
to the nearest integer. This means that, for example, rgb(0 0 1) != rgb(0 0 0.6)
. This matches the latest version of the CSS spec and browser behavior.
Potentially breaking compatibility fix: Passing large positive or negative
values to color.adjust()
can now cause a color's channels to go outside that
color's gamut. In most cases this will currently be clipped by the browser and
end up showing the same color as before, but once browsers implement gamut
mapping it may produce a different result.
Add support for CSS Color Level 4 [color spaces]. Each color value now tracks its color space along with the values of each channel in that color space. There are two general principles to keep in mind when dealing with new color spaces:
With the exception of legacy color spaces (rgb
, hsl
, and hwb
), colors
will always be emitted in the color space they were defined in unless
they're explicitly converted.
The color.to-space()
function is the only way to convert a color to
another color space. Some built-in functions may do operations in a
different color space, but they'll always convert back to the original space
afterwards.
rgb
colors can now have non-integer channels and channels outside the normal
gamut of 0-255. These colors are always emitted using the rgb()
syntax so
that modern browsers that are being displayed on wide-gamut devices can
display the most accurate color possible.
Add support for all the new color syntax defined in Color Level 4, including:
oklab()
, oklch()
, lab()
, and lch()
functions;hwb()
function that matches the space-separated CSS syntax;color()
function that supports the srgb
, srgb-linear
,
display-p3
, a98-rgb
, prophoto-rgb
, rec2020
, xyz
, xyz-d50
, and
xyz-d65
color spaces.Add new functions for working with color spaces:
color.to-space($color, $space)
converts $color
to the given $space
. In
most cases this conversion is lossless—the color may end up out-of-gamut for
the destination color space, but browsers will generally display it as best
they can regardless. However, the hsl
and hwb
spaces can't represent
out-of-gamut colors and so will be clamped.
color.channel($color, $channel, $space: null)
returns the value of the
given $channel
in $color
, after converting it to $space
if necessary.
It should be used instead of the old channel-specific functions such as
color.red()
and color.hue()
.
color.same($color1, $color2)
returns whether two colors represent the same
color even across color spaces. It differs from $color1 == $color2
because
==
never consider colors in different (non-legacy) spaces as equal.
color.is-in-gamut($color, $space: null)
returns whether $color
is
in-gamut for its color space (or $space
if it's passed).
color.to-gamut($color, $space: null)
returns $color
constrained to its
space's gamut (or to $space
's gamut, if passed). This is generally not
recommended since even older browsers will display out-of-gamut colors as
best they can, but it may be necessary in some cases.
color.space($color)
: Returns the name of $color
's color space.
color.is-legacy($color)
: Returns whether $color
is in a legacy color
space (rgb
, hsl
, or hwb
).
color.is-powerless($color, $channel, $space: null)
: Returns whether the
given $channel
of $color
is powerless in $space
(or its own color
space). A channel is "powerless" if its value doesn't affect the way the
color is displayed, such as hue for a color with 0 chroma.
color.is-missing($color, $channel)
: Returns whether $channel
's value is
missing in $color
. Missing channels can be explicitly specified using the
special value none
and can appear automatically when color.to-space()
returns a color with a powerless channel. Missing channels are usually
treated as 0, except when interpolating between two colors and in
color.mix()
where they're treated as the same value as the other color.
Update existing functions to support color spaces:
hsl()
and color.hwb()
no longer forbid out-of-bounds values. Instead,
they follow the CSS spec by clamping them to within the allowed range.
color.change()
, color.adjust()
, and color.scale()
now support all
channels of all color spaces. However, if you want to modify a channel
that's not in $color
's own color space, you have to explicitly specify the
space with the $space
parameter. (For backwards-compatibility, this
doesn't apply to legacy channels of legacy colors—for example, you can still
adjust an rgb
color's saturation without passing $space: hsl
).
color.mix()
and color.invert()
now support the standard CSS algorithm
for interpolating between two colors (the same one that's used for gradients
and animations). To use this, pass the color space to use for interpolation
to the $method
parameter. For polar color spaces like hsl
and oklch
,
this parameter also allows you to specify how hue interpolation is handled.
color.complement()
now supports a $space
parameter that indicates which
color space should be used to take the complement.
color.grayscale()
now operates in the oklch
space for non-legacy colors.
color.ie-hex-str()
now automatically converts its color to the rgb
space
and gamut-maps it so that it can continue to take colors from any color
space.
The following functions are now deprecated, and uses should be replaced with the new color-space-aware functions defined above:
The color.red()
, color.green()
, color.blue()
, color.hue()
,
color.saturation()
, color.lightness()
, color.whiteness()
, and
color.blackness()
functions, as well as their global counterparts, should
be replaced with calls to color.channel()
.
The global adjust-hue()
, saturate()
, desaturate()
, lighten()
,
darken()
, transaprentize()
, fade-out()
, opacify()
, and fade-in()
functions should be replaced by color.adjust()
or color.scale()
.
Add a global-builtin
future deprecation, which can be opted-into with the
--future-deprecation
flag or the futureDeprecations
option in the JS or
Dart API. This emits warnings when any global built-in functions that are
now available in sass:
modules are called. It will become active by default
in an upcoming release alongside the @import
deprecation.
Added a ColorSpace
class which represents the various color spaces defined
in the CSS spec.
Added SassColor.space
which returns a color's color space.
Added SassColor.channels
and .channelsOrNull
which returns a list
of channel values, with missing channels converted to 0 or exposed as null,
respectively.
Added SassColor.isLegacy
, .isInGamut
, .channel()
, .isChannelMissing()
,
.isChannelPowerless()
, .toSpace()
, .toGamut()
, .changeChannels()
, and
.interpolate()
which do the same thing as the Sass functions of the
corresponding names.
SassColor.rgb()
now allows out-of-bounds and non-integer arguments.
SassColor.hsl()
and .hwb()
now allow out-of-bounds arguments.
Added SassColor.hwb()
, .srgb()
, .srgbLinear()
, .displayP3()
,
.a98Rgb()
, .prophotoRgb()
, .rec2020()
, .xyzD50()
, .xyzD65()
,
.lab()
, .lch()
, .oklab()
, .oklch()
, and .forSpace()
constructors.
Deprecated SassColor.red
, .green
, .blue
, .hue
, .saturation
,
.lightness
, .whiteness
, and .blackness
in favor of
SassColor.channel()
.
Deprecated SassColor.changeRgb()
, .changeHsl()
, and .changeHwb()
in
favor of SassColor.changeChannels()
.
Added SassNumber.convertValueToUnit()
as a shorthand for
SassNumber.convertValue()
with a single numerator.
Added InterpolationMethod
and HueInterpolationMethod
which collectively
represent the method to use to interpolate two colors.
While the legacy API has been deprecated since we released the modern API, we
now emit warnings when the legacy API is used to make sure users are aware
that it will be removed in Dart Sass 2.0.0. In the meantime, you can silence
these warnings by passing legacy-js-api
in silenceDeprecations
when using
the legacy API.
Modify SassColor
to accept a new space
option, with support for all the
new color spaces defined in Color Level 4.
Add SassColor.space
which returns a color's color space.
Add SassColor.channels
and .channelsOrNull
which returns a list of channel
values, with missing channels converted to 0 or exposed as null, respectively.
Add SassColor.isLegacy
, .isInGamut()
, .channel()
, .isChannelMissing()
,
.isChannelPowerless()
, .toSpace()
, .toGamut()
, .change()
, and
.interpolate()
which do the same thing as the Sass functions of the
corresponding names.
Deprecate SassColor.red
, .green
, .blue
, .hue
, .saturation
,
.lightness
, .whiteness
, and .blackness
in favor of
SassColor.channel()
.
Add Color
SassScript value, with support for all the new color spaces
defined in Color Level 4.
Remove RgbColor
, HslColor
and HwbColor
SassScript values.
FAQs
A pure JavaScript implementation of Sass.
The npm package sass receives a total of 11,835,594 weekly downloads. As such, sass popularity was classified as popular.
We found that sass demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 3 open source maintainers collaborating on the project.
Did you know?
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