1.9 KiB
| title | introduction |
|---|---|
| Breaking Change: Strict Unary Operators | Sass has historically allowed `-` and `+` to be used in ways that make it ambiguous whether the author intended them to be a binary or unary operator. This confusing syntax is being deprecated. |
How is this property compiled?
{% codeExample 1, false %} $size: 10px;
div { margin: 15px -$size; }
$size: 10px
div margin: 15px -$size {% endcodeExample %}
Some users might say "the - is attached to $size, so it should be margin: 20px -10px". Others might say "the - is between 20px and $size, so it
should be margin: 5px." Sass currently agrees with the latter opinion, but the
real problem is that it's so confusing in the first place! This is a natural but
unfortunate consequence of CSS's space-separated list syntax combined with
Sass's arithmetic syntax.
That's why we're moving to make this an error. In the future, if you want to use
a binary - or + operator (that is, one that subtracts or adds two numbers),
you'll need to put whitespace on both sides or on neither side:
- Valid:
15px - $size - Valid:
(15px)-$size - Invalid:
15px -$size
If you want to use a unary - or + operator as part of a space-separated
list, you'll (still) need to wrap it in parentheses:
- Valid:
15px (-$size)
Transition Period
{% compatibility '1.55.0', false, null, false %}{% endcompatibility %}
We'll make this an error in Dart Sass 2.0.0, but until then it'll just emit a deprecation warning.
{% render 'documentation/snippets/silence-deprecations' %}
Automatic Migration
You can use the Sass migrator to automatically update your stylesheets to add
a space after any - or + operators that need it, which will preserve the
existing behavior of these stylesheets.
$ npm install -g sass-migrator
$ sass-migrator strict-unary **/*.scss