Breaking Change: Mixed Declarations

The Story So FarThe Story So Far permalink

Historically, if you mixed together nested rules and declarations in Sass, it would pull all the declarations to the beginning of the rule to avoid duplicating the outer selector more than necessary. For example:

.example {
  color: red;

  a {
    font-weight: bold;
  }

  font-weight: normal;
}

.example
  color: red

  a
    font-weight: bold


  font-weight: normal

.example {
  color: red;
  font-weight: normal;
}

.example a {
  font-weight: bold;
}

When plain CSS Nesting was first introduced, it behaved the same way. However, after some consideration, the CSS working group decided it made more sense to make the declarations apply in the order they appeared in the document, like so:

.example {
  color: red;

  a {
    font-weight: bold;
  }

  font-weight: normal;
}

.example
  color: red

  a
    font-weight: bold


  font-weight: normal

.example {
  color: red;
}

.example a {
  font-weight: bold;
}

.example {
  font-weight: normal;
}

Deprecating the Old WayDeprecating the Old Way permalink

Compatibility:

Dart Sass

since 1.77.7

LibSass

✗

Ruby Sass

✗

The use of declarations after nested rules is currently deprecated in Sass, in order to notify users of the upcoming change and give them time to make their stylesheets compatible with it. In a future release, Dart Sass will change to match the ordering produced by plain CSS nesting.

If you want to opt into the new CSS semantics early, you can wrap your nested declarations in & {}:

.example {
  color: red;

  a {
    font-weight: bold;
  }

  & {
    font-weight: normal;
  }
}

.example
  color: red

  a
    font-weight: bold


  &
    font-weight: normal

.example {
  color: red;
}
.example a {
  font-weight: bold;
}
.example {
  font-weight: normal;
}

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

Sass provides a powerful suite of options for managing which deprecation warnings 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 of deprecation warning five times before it silences additional warnings. This helps ensure that users know when they need to be aware of an upcoming breaking change without creating an overwhelming amount of console noise.

If you run Sass in verbose mode instead, it will print every deprecation warning it encounters. This can be useful for tracking the remaining work to be done when fixing deprecations. You can enable verbose mode using the --verbose flag on the command line, or the verbose option in the JavaScript API.

Silencing Deprecations in DependenciesSilencing Deprecations in Dependencies permalink

Sometimes, your dependencies have deprecation warnings that you can’t do anything about. You can silence deprecation warnings from dependencies while still printing them for your app using the --quiet-deps flag on the command line, or the quietDeps option in the JavaScript API.

For the purposes of this flag, a "dependency" is any stylesheet that’s not just a series of relative loads from the entrypoint stylesheet. This means anything that 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 can silence warnings for that specific deprecation using the --silence-deprecation flag on the command line, or the silenceDeprecations option in the JavaScript API.