converting some CSS to Sass, for example:
.ptn,
.pvn,
.pan{padding-top:0px !important}
to this
#mixin ptn {padding-top:0px !important}
#mixin pvn {padding-top:0px !important}
#mixin pan {padding-top:0px !important}
but wishing i could do something more like this
#mixin ptn,
#mixin pvn,
#mixin pan {padding-top:0px !important}
is something along these lines possible?
thanks!
How about
#mixin nopadding{ padding-top:0px !important }
.ptn,
.pvn,
.pan{ #include nopadding }
?
Sass is about Reusability, so try to keep the code DRY by breaking this up into a new mixin.
Additionally you could write something like this:
#mixin nopadding{ padding-top:0px !important }
#mixin anothermixin{ #include nopadding; ... }
normalselector{ #include anothermixin; }
Alternatively you can use the #extend feature to be a little cleaner, depending on your purposes.
So if you have:
.ptn { padding-top:0px !important; }
You can do this anywhere else in your code (it doesn't require it to go after for scoping purposes, like mixins do):
.pvn { #extend .ptn; /* pvn-specific rules can still go here */ }
.pan { #extend .ptn; /* pan-specific rules can still go here */}
This will output as such:
.ptn, .pvn, .pan { padding-top:0px !important; }
.pvn { /* pvn-specific rules can still go here */ }
.pan { /* pan-specific rules can still go here */ }
This can be a cleaner output than using mixins, which would duplicate the code. This is particularly useful for larger blocks of code, like clear fixes. But mixins do have their place.
Speaking of things having their place… is that !important really necessary? ;-)
Related
aye folks!
i tried to build a sass mixin for css custom properties to make work a little bit easier.
my attempt does look like this:
#mixin mixin($value) {
background: unquote('$')#{$value};
background: var(--#{$value}, unquote('$')#{$value});
}
the output looks like this:
.example {
background: $value;
background: var(--colour, $value);
}
BUT sass doesn't convert my $value into the actual thing. the $value part end up in my final css file and ofc this doesn't work.
i tried to find a solution online but i'm either to dumb to find it or there isn't one. anyone here has an idea what i'm doing wrong?
I have try your code with this example:
#mixin mixin($value) {
background: unquote('$')#{$value};
background: var(--#{$value}, unquote('$')#{$value});
}
.example {
#include mixin(colour)
}
and it works.
The output is:
.example {
background: $colour;
background: var(--colour, $colour);
}
is what you want? Sorry but I don't have the authorization for add comment so I create this answer.
Edit: you can create a different mixin like this:
#mixin mixin($value, $color) {
background: $color;
background: var(--#{$value}, $color);
}
This help you to solve your problem?
I'm using the SASS port of Bootstrap, and I'm wondering if there's any difference between using the pre-defined mixins and using SASS's #extend.
For instance, if I have:
<div class="wrapper">
Some content here....
</div>
Is there any difference between doing
.wrapper {
#include make-row();
}
and
.wrapper {
#extend .row;
}
?
If there's no difference, are there other mixins that aren't equivalent to a single #extend statement? If there aren't such mixins, why do the mixins even exist?
The big difference between #extend and a mixin is the way the css is compiled. It doesn't look like much in simple examples, but the differences and implications are significant and can be a real headache in the wild if used carelessly. #extend is a little bit like fools gold, looks great at first, but ...
Let's look at a simple example:
#extend
.row {
width: 50px;
}
.new-row {
#extend .row;
}
.another-row {
#extend .row;
}
compiles into:
.row,
.new-row,
.another-row {
width: 50px;
}
mixin
#mixin row() {
width: 50px;
}
.new-row {
#include row();
}
.another-row {
#include row();
}
compiles into:
.new-row {
width: 50px;
}
.another-row {
width: 50px;
}
A mixin includes the properties everywhere it is hit - copying them each time - whereas an #extend groups the selectors and defines the properties once. This isn't immediately obvious, because the difference is in the compiled css but it has some important implications:
Load order
With #extend the selectors will be grouped at the first point in the sass where they are encountered which can lead to some weird over-riding. If you define a selector and use #extend to bring in a property to and try to override a property defined earlier in your sass, but after the point at which the extended properties are grouped in the css then the override will not work. This can be quite perplexing.
Consider this logically ordered set of css definitions and the likely HTML: <div class='row highlight-row'></div>:
.red-text {
color: red;
}
.row {
color: green;
}
.highlight-row {
#extend .red-text;
}
compiles into:
.red-text,
.highlight-row {
color: red;
}
.row {
color: green;
}
So even though the sass ordering makes it look like the row colour would be red, the compiled css will make it green
Poor groupings
#extend can result in poorly grouped selectors in the resulting css. You can end up with thirty or forty unrelated things all sharing the same property for example. Using #extend for fonts is a good example of this.
Nesting
If you are using deeply nested sass (which is not good, btw) and you use #extend you will duplicate the fully nested selector for every #extend you use, resulting in bloated css. I've seen this a lot:
.selector-1 .selector-2 .selector-3 .selector-4,
.selector-1 .selector-2 .selector-3 .selector-4 a,
.selector-1 .selector-2 .selector-3 .selector-4 li,
.selector-1 .selector-2 .selector-3 .selector-4 td {
font-family: arial;
}
If you're new to SASS it pays to look at the compiled css.
Media queries
#extend do not work inside media queries, because media queries are not selectors.
Conclusion
My rule of thumb is to use an #extend over a mixin if you have no parameters and if you can reasonably define the #extend and share it amongst a few tightly related selectors that exist nearby in the sass, for example, in the same file that defines a sass module. Buttons are a good example of well used #extend:
%button {
padding: 10px;
}
.call-to-action {
#extend %button;
background-color: $green;
}
.submit {
#extend %button;
background-color: $grey;
}
The best article to help make the choice is here
PS, the % sign is a use of placeholder extends
In LESS you can do that:
.my-class {
color:blue;
}
.my-other-class {
.my-class;
font-size:14px;
}
In Sass it can be done with #extend:
.my-other-class {
#extend .my-class;
font-size:14px;
}
But here, in comment to main text, MartinAnsty says that it might not work with #media directives.
So functionality of #extend in Sass and mixins in LESS are fully equal?
It will work, Martin means the mediaquery will also be extended, if class have them. So if .my-class has got media query max-width 500{ color: blue }, and min-width 600 { color: green } you have to remeber that it will be executed in extend.
On their website, the first feature is "Experience cleaner markup without presentational classes.", how do they solve this problem?
I think what Compass has to offer in order to allow us to create cleaner and semantic markup comes for free if you already use SASS alone.
By instance take this trivial example:
Some Mixins
#mixin box {
display: block;
}
#mixin sized_box($width:auto, $height:auto) {
#include box;
width: $width;
height: $height;
}
#mixin floated_box($direction:none, $width:auto, $height:auto) {
#include sized_box($width, $height);
float: $direction;
}
#mixin left_box($width:auto, $height:auto) {
#include floated_box(left, $width, $height);
}
#mixin right_box($width:auto, $height:auto) {
#include floated_box(right, $width, $height);
}
A Placeholder
// divs will be red
div%colored_floating {
#include left_box;
background-color: #ff0000;
}
// paragraphs will be blue
p%colored_floating {
#include right_box;
background-color: #0000ff;
}
Our stylesheet
// if #some.selector * turns out to be a div it will be red,
// and if it is a paragraph it will be blue
#some.selector *{
#extend %colored_floating;
}
Finally on your markup, you don't need any presentational classes
Except for those to make the placeholders more specific, of course.
<section id="some" class="selector">
<div>This will float and it will be red</div>
<p>But this will float right and will be blue</p>
</section>
You could always do:
// to make the placeholders absolutely generic to the whole markup,
* {
#extend %colored_floating;
}
Again, sorry for the very trivial example, but hopefully it will give you an idea on how to get rid of the presentational classes on your markup, aiming to pure semantic content.
What Compass gives us in addition is a complete framework of these mixins, placeholders and so on, ready to be used for good.
Cheers!
I have an item class and a compact "modifier" class:
.item { ... }
.item.compact { /* styles to make .item smaller */ }
This is fine. However, I'd like to add a #media query that forces the .item class to be compact when the screen is small enough.
On first thought, this is what I tried to do:
.item { ... }
.item.compact { ... }
#media (max-width: 600px) {
.item { #extend .item.compact; }
}
But this generates the following error:
You may not #extend an outer selector from within #media. You may only
#extend selectors within the same directive.
How would I accomplish this using SASS without having to resort to copy/pasting styles?
The simple answer is: you can't because Sass can't (or won't) compose the selector for it. You can't be inside of a media query and extend something that's outside of a media query. It certainly would be nice if it would simply take a copy of it instead of trying to compose the selectors. But it doesn't so you can't.
Use a mixin
If you have a case where you're going to be reusing a block of code inside and outside of media queries and still want it to be able to extend it, then write both a mixin and an extend class:
#mixin foo {
// do stuff
}
%foo {
#include foo;
}
// usage
.foo {
#extend %foo;
}
#media (min-width: 30em) {
.bar {
#include foo;
}
}
Extend the selector within a media query from the outside
This won't really help your use case, but it is another option:
%foo {
#media (min-width: 20em) {
color: red;
}
}
#media (min-width: 30em) {
%bar {
background: yellow;
}
}
// usage
.foo {
#extend %foo;
}
.bar {
#extend %bar;
}
Wait until Sass lifts this restriction (or patch it yourself)
There are a number of ongoing discussions regarding this issue (please don't contribute to these threads unless you have something meaningful to add: the maintainers are already aware that users desire this functionality, it's just a question of how to implement it and what the syntax should be).
https://github.com/sass/sass/issues/1050
https://github.com/sass/sass/issues/456
For the record, here is how I ended up solving the problem with only duplicating generated styles once:
// This is where the actual compact styles live
#mixin compact-mixin { /* ... */ }
// Include the compact mixin for items that are always compact
.item.compact { #include compact-mixin; }
// Here's the tricky part, due to how SASS handles extending
.item { ... }
// The following needs to be declared AFTER .item, else it'll
// be overridden by .item's NORMAL styles.
#media (max-width: 600px) {
%compact { #include compact-mixin; }
// Afterwards we can extend and
// customize different item compact styles
.item {
#extend %compact;
/* Other styles that override %compact */
}
// As shown below, we can extend the compact styles as many
// times as we want without needing to re-extend
// the compact mixin, thus avoiding generating duplicate css
.item-alt {
#extend %compact;
}
}
I believe SASS/SCSS does not support the #extend directive inside of a media query. http://designshack.net/articles/css/sass-and-media-queries-what-you-can-and-cant-do/
You might need to use a mixin instead, though the code bloat needs to be weighed against your objective.
This is the cleanest, partial solution I've found. It takes advantage of #extend where possible and falls back to mixins when inside media queries.
Cross-Media Query #extend Directives in Sass
See the article for full details but the gist is that you call a mixin 'placeholder' that then decides whether to output #extend or an #include.
#include placeholder('clear') {
clear: both;
overflow: hidden;
}
.a {
#include _(clear);
}
.b {
#include _(clear);
}
.c {
#include breakpoint(medium) {
#include _(clear);
}
}
Ultimately it may not be better than just using mixins, which is currently the accepted answer.
I use breakpoints, but it's the same idea:
#mixin bp-small {
#media only screen and (max-width: 30em) {
#content;
}
How to use it:
.sidebar {
width: 60%;
float: left;
#include bp-small {
width: 100%;
float: none;
}
}
There is a text about mixins where you can find out more about this option.
Could you restructure?
.compact { //compact-styles }
.item {}
.item.compact { #extend .compact }
#media (max-width: 600px) {
.item { #extend .compact; }
}
If I understand the documentation correctly, that should work. I think the reason the way you're trying won't work is that it doesn't see .item.compact when it's parsing the #extend, but that's an uninformed guess, so take that with a truck load of salt! :)