Breaking Change: Media Queries Level 4

Sass has added support for theCSS Media Queries Level 4 specification. This originally conflicted with some Sass-specific syntax, so this syntax was deprecated and is now interpreted according to theCSS standard.

Compatibility:
Dart Sass
since 1.56.0
LibSass
✗
Ruby Sass
✗

Because Sass supports almost any Sass expression in parenthesized mediaconditions, there were a few constructs whose meaning was changed by adding fullsupport for Media Queries Level 4. Specifically:

  • @media (not (foo)) was historically interpreted by Sass as meaning@media (#{not (foo)}), and so compiled to@media (false).

  • @media ((foo) and (bar)) and@media ((foo) or (bar)) were similarlyinterpreted as SassScript’s logical operators, compiling to@media (bar) and@media (foo) respectively.

Fortunately, these came up very infrequently in practice.

Transition PeriodTransition Period permalink

Compatibility:
Dart Sass
since 1.54.0
LibSass
✗
Ruby Sass
✗

First, we emitted deprecation warnings for the previous ambiguous cases. Thesewill have suggestions for how to preserve the existing behavior or how to usethe newCSS syntax.

Can I Silence the Warnings?Can I Silence the Warnings? permalink

Sass provides a powerful suite of options for managing which deprecationwarnings you see and when.

Terse and Verbose ModeTerse and Verbose Mode permalink

By default, Sass runs in terse mode, where it will only print each type ofdeprecation warning five times before it silences additional warnings. Thishelps ensure that users know when they need to be aware of an upcoming breakingchange without creating an overwhelming amount of console noise.

If you run Sass in verbose mode instead, it will printevery deprecationwarning it encounters. This can be useful for tracking the remaining work to bedone when fixing deprecations. You can enable verbose mode usingthe--verbose flag on the command line, ortheverbose option in the JavaScript API.

⚠️ Heads up!

When running from theJSAPI, Sass doesn’t share any information acrosscompilations, so by default it’ll print five warnings foreach stylesheetthat’s compiled. However, you can fix this by writing (or asking the author ofyour favorite framework’s Sass plugin to write) acustomLogger that onlyprints five errors per deprecation and can be shared across multiple compilations.

Silencing Deprecations in DependenciesSilencing Deprecations in Dependencies permalink

Sometimes, your dependencies have deprecation warnings that you can’t doanything about. You can silence deprecation warnings from dependencies whilestill printing them for your app usingthe--quiet-deps flag on the command line, orthequietDeps option in the JavaScript API.

For the purposes of this flag, a "dependency" is any stylesheet that’s not justa series of relative loads from the entrypoint stylesheet. This means anythingthat comes from a load path, and most stylesheets loaded through custom importers.

Silencing Specific DeprecationsSilencing Specific Deprecations permalink

If you know that one particular deprecation isn’t a problem for you, you cansilence warnings for that specific deprecation usingthe--silence-deprecation flag on the command line, orthesilenceDeprecations option in the JavaScript API.