mirror of
https://github.com/danog/sass-site.git
synced 2024-12-12 17:37:36 +01:00
69 lines
2.1 KiB
Plaintext
69 lines
2.1 KiB
Plaintext
---
|
|
title: 'Breaking Change: Strict Unary Operators'
|
|
introduction: >
|
|
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.
|
|
---
|
|
|
|
{% markdown %}
|
|
How is this property compiled?
|
|
{% endmarkdown %}
|
|
|
|
{% codeExample 'strict-unary', false %}
|
|
$size: 10px;
|
|
|
|
div {
|
|
margin: 15px -$size;
|
|
}
|
|
===
|
|
$size: 10px
|
|
|
|
div
|
|
margin: 15px -$size
|
|
{% endcodeExample %}
|
|
|
|
{% markdown %}
|
|
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 'dart: "1.55.0"', 'libsass: false', 'ruby: 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 'doc_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.
|
|
|
|
[the Sass migrator]: https://github.com/sass/migrator#readme
|
|
|
|
```shellsession
|
|
$ npm install -g sass-migrator
|
|
$ sass-migrator strict-unary **/*.scss
|
|
```
|
|
{% endmarkdown %}
|