How to stop #mixin in SCSS from duplicating CSS? - sass

Question

I want to use one CSS style for two classes with mixin, but when I use mixin the final result will be 2 classes with the same CSS.
I have shared my code example below:
#mixin btnhover {
background-color: $bg-cl-blc;
color: $txt-cl-ff;
}
.btn-base {
font-size: 15px;
&:hover {
#include btnhover;
}
}
.btn-otln {
font-size: 15px;
&:hover {
#include btnhover;
}
}
**OUTPUT CSS**
.btn-base:hover {
background-color: #000;
color: #fff;
}
.btn-otln:hover {
background-color: #000;
color: #fff;
}

Answer 1

This is how Sass works - it allows for better organisation of the code, but this code is then compiled, retaining functionality and not caring about other aspects.
If you really care about how the output code is structured, I would suggest to create a separate style for the classes with the hover effect:
#mixin btnhover {
background-color: #000;
color: #fff;
}
.btn-base {
font-size: 15px;
}
.btn-otln {
font-size: 15px;
}
.btn-base:hover,
.btn-otln:hover {
#include btnhover;
}
But in this approach, the use of mixin (and Sass) is questionable (in this exact case).
Generally, when you use Sass (or any other compiled language), you don't really care about the output CSS.

Answer 2

This won't be your answer, but I want to show you another way to make a mixin
#mixin btnhover($back, $color) {
background: $back;
color: $color;
}
When you use it, you can plug in the values
#include mixin btnhover($bg-cl-blc, $txt-cl-ff)
That way you can use the mixin over and over in different places with different values

Answer 3

Just discovered this recently myself, it's a concept called 'placeholders' in SASS syntax (see example below). I've done my best to apply it to your situation below....
Put this in your .scss file:
$bg-cl-blc: #ff211a;
$txt-cl-ff: #fff;
$btn-base-size: 15px;
%btnhover {
background-color: $bg-cl-blc;
color: $txt-cl-ff;
}
%btn-common {
font-size: $btn-base-size;
}
.btn-base {
#extend %btn-common;
&:hover {
#extend %btnhover;
}
}
.btn-otln {
#extend %btn-common;
&:hover {
#extend %btnhover;
}
}
CSS output will look like this
.btn-otln:hover, .btn-base:hover {
background-color: #ff211a;
color: #fff;
}
.btn-otln, .btn-base {
font-size: 15px;
}
Great article written up on this here:
https://dev.to/kemotiadev/are-sass-mixins-really-that-lightweight-and-what-are-placeholders-119i