I'd like to write a plugin that can generate a LESS function named alt that can do the following transformation:
.button {
background-color: alt(red, blue);
color: alt(black, white);
}
And output the following:
.button {
background-color: red;
color: black;
body.alt & {
background-color: blue;
color: white;
}
}
There doesn't seem to be much documentation about writing LESS plugins on the site, so hoping someone can provide an example of how this might be written :) Thanks!
I think a mixin would be best for this. Something like the following LESS:
.alt(#property, #primary-color, #alternate-color) {
#{property}: #primary-color;
body.alt & {
#{property}: #alternate-color;
}
}
.button {
.alt(background-color, red, blue);
.alt(color, black, white);
}
Which will compile to the following CSS:
.button {
background-color: red;
color: black;
}
body.alt .button {
background-color: blue;
}
body.alt .button {
color: white;
}
Related
I have a LESS mixin. When I apply this to an element I want it be styled slightly differently if a body class is present.
This:
.mixin() {
font-weight: bold;
color: red;
}
.element {
.mixin()
}
Outputs to this:
.element {
font-weight: bold;
color: red;
}
But I also want this to be outputted:
.body-class .element {
color: blue;
}
You can define your mixin this way:
.mixin() {
font-weight: bold;
color: red;
.body-class & {
color: blue;
}
}
How can I inherit from a class which name is composed using the & character (e.g. &-rule), please?
Desired Output
.prefix-rule-extended,
.prefix-rule {
color: white;
}
.prefix-rule-extended {
background-color: black;
}
or
.prefix-rule {
color: white;
}
.prefix-rule-extended {
color: white;
background-color: black;
}
Non-working Approaches
.prefix {
&-rule {
color: white;
}
}
plus
.prefix-rule-extended:extend(.prefix-rule) {
background-color: black;
}
or
.prefix-rule-extended {
.prefix-rule();
background-color: black;
}
Ideal Approach
.prefix {
&-rule {
color: white;
}
&-rule-extended:extend(&-rule) {
background-color: black;
}
}
Note 1: I know :extend(&-rule) is currently not supported.
Note 2: .prefix-rule is not so simple, i.a. there are nested rules inside so the following will not work:
.prefix {
&-rule {
color: white;
&-extended {
background-color: black;
}
}
}
Thank you.
(Ok, so as always to not leave this one w/o an answer - a summary of comments above):
Currently it's impossible to extend that kind of things. For the moment extend can't match selector identifiers generated via "concatenation" so .prefix {&.rule { ... would be a valid extend target (as it's "two elements" -> "two identifiers") but .prefix {&-rule { ... won't (since it's "two elements" -> "one identifier").
So if you plan to use extend don't be keen on such kind of nesting, keep it more simple.
Here are three valid Less snippets (each having its pros and cons) to get the desired CSS output.
1:
.prefix-rule {
color: white;
&-extended:extend(.prefix-rule) {
background-color: black;
}
}
2:
.prefix-rule {
&, &-extended {
color: white;
}
&-extended {
background-color: black;
}
}
3:
.rule-base {
color: white;
}
.prefix-rule {
&:extend(.rule-base);
&-extended:extend(.rule-base) {
background-color: black;
}
}
I have a mixin that accepts an argument that I want to pass into a variable.
#mixin my_mixin($arg) {
background-color: $state-#{$arg}-text;
}
Interpolation of variable names is currently not possible in SASS. Here is the issue that discusses.
However, you may use interpolation of placeholders:
%my-dark-styles {
background-color: #000;
}
%my-white-styles {
background-color: #FFF;
}
#mixin my_mixin($arg) {
#extend %my-#{$arg}-styles;
}
.header {
#include my_mixin("dark");
}
.footer {
#include my_mixin("white");
}
This compiles to:
.header {
background-color: #000;
}
.footer {
background-color: #FFF;
}
Since Sass 3.3 you can use maps also https://sass-lang.com/blog/sass-33-is-released
Here is an example:
$state-light-text : #FFFFFF;
$state-dark-text : #000000;
$color-map: ( //create a array to support the two colors light and dark
light: $state-light-text,
dark: $state-dark-text
);
#each $color-key, $color-var in $color-map {
.myclass--#{$color-key} { //will generate .myclass--light .myclass--dark
background-color: $color-var; // equal $state-light-text or $state-dark-text
}
}
It will compile into:
.myclass--light {
background-color: #FFFFFF;
}
.myclass--dark {
background-color: #000000;
}
I am starting out with Less and one of the reasons I wanted to is because of the ligthen() function. So my first attempt was to do something with that.
This is my HTML
<div class="box blue">
<div class="boxbar">Foo</div>
blue
</div>
I finally got it working, but I doubt it's supposed be like this:
#blue: #468ACE;
#green: #41A53D;
#red: #9C2525;
#purple: #8938BF;
div
{
padding: 10px;
}
.blue {
background-color: #blue;
.boxbar { background-color: lighten(#blue, 10%); }
}
.green {
background-color: #green;
.boxbar { background-color: lighten(#green, 10%); }
}
.red {
background-color: #red;
.boxbar { background-color: lighten(#red, 10%); }
}
.purple {
background-color: #purple;
.boxbar { background-color: lighten(#purple, 10%); }
}
.boxbar
{
height: 10px;
}
How can I refactor this? Surely it must be easier to say "get your parent color, and lighten it a bit". I tried a couple of things: inherit (was worth a shot!), have the lightened versions inside .boxcar. But this obviously compiled to .boxcar .blue.. which is not what I want and I ended with what you can see here.. it works.. but it doesn't feel right. Then I would need to write code for every new color I introduce..
I am not completely sure what your desired solution would be ... but maybe something like making a mixin would help you from having to write so much stuff out.
LESS:
.bgmixin(#color) {
(~".#{color}") {
background-color: ##color;
.boxbar {
background-color: lighten(##color, 10%);
}
}
}
#blue: #468ACE;
#green: #41A53D;
#red: #9C2525;
.bgmixin("blue");
.bgmixin("green");
.bgmixin("red");
CSS:
.blue{
background-color: #468ace;
}
.blue .boxbar {
background-color: #6ea3d9;
}
.green{
background-color: #41a53d;
}
.green .boxbar {
background-color: #59c055;
}
.red{
background-color: #9c2525;
}
.red .boxbar{
background-color: #c52f2f;
}
Update:
In LESS>=1.4 you would want to use something like this to interpolate the class name from the color name:
.bgmixin(#color) {
#classname: ~"#{color}";
.#{classname} {
background-color: ##color;
.boxbar {
background-color: lighten(##color, 10%);
}
}
}
Let's say I have the following Less setup:
.box {
border: 1px solid #333;
&.error {
background-color: Red;
}
}
If I wanted to declare another class which applied the full style of .box.error, as .error-box for example, what's the correct syntax?
If I use:
.error-box {
.box.error;
}
All I get is the red background, with no border. I've tried many different combinations, but I always get a syntax error.
I plugged in your less as so:
.box {
border: 1px solid #333;
&.error {
background-color:red;
}
}
.error-box {
.box;
}
and the CSS output was this:
.box {
border: 1px solid #333;
}
.box.error {
background-color: red;
}
.error-box {
border: 1px solid #333;
}
.error-box.error {
background-color: red;
}
were you wanting the .error-box class to alone receive both styles? The only way I can think of doing that would be:
.error-bg {
background:red;
}
.box {
border:1px solid #333;
&.error {
.error-bg;
}
}
.error-box {
.box;
.error-bg;
}