Sass
Introduction
Advantages
- Named Colors
Prior to variables in CSS this was just allowed the user to define a color
- Removes Duplication
Saas allows you to put common code into function to reduce duplication
- Cascading is simpler
Saas provide a way to inherit from other declaration
- Improved Calculations
Saas allows you to calculate based on other another value e.g. fonts +2px
- Better Imports
Saas allows combining of imports to reduce the number of round trips.
LESS
Intro
- Compiles to CSS
- All CSS is valid LESS
Client
The less.js will transform the file to css.
<head>
<link rel="stylesheet/ess"
type="text/css"
href="css/my.less">
<script src="js/less.js"
type="text/javascript">
</script>
</head>
Server
We can install using
npm i less
And use with
const less = require('less')
Importing
We just attach the @import for this. The approach is sometimes to put type of information into a file. E.g. colors or mixins
@import "init"
@import "color"
@import "mixens"
Variables
LESS allows us to use variables. Must start with an @ and a letter. All variables of constants so cannot be reassigned. We can store Color, Units, Strings and complex types.
// color
@main-color: Black;
// Complex type
@borderIain: 1px #000 Solid 0 0;
Functions
Functions can be used with colors but you have to use the # values and not the name.
color: lighten(@color, 10%)
color: darken(@color, 10%)
@hue: hue(@color)
@sat: saturation(@color)
@light: lightness(@color)
@alpha: alpha(@color)
Operations
font-size: 4px + 4
color: #FFF / 4 // $404040
Mixins
Mixins allow us to define functions to reduce duplication. E.g. for rounded corners. Note the 5px does not need to be specified. It is just a default value
.rounded-corners-all(@size: 5px) {
border-radius: @size;
-webkit-border-radius: @size;
-moz-border-radius: @size
}
#form
{
.rounded-corners-all(5px);
}
We can overload the Mixen too
.color(@color) {
color: @color;
}
.color(@color, @factor) {
color: lighten(@color, @factor;
}
We can provide guards to only perform action if satisfied
.color(@color) when (alpha(@color) < 50%) {
color: transparent;
}
Nested Rules
In css we might write
nav {
font-size: 14px;
font-weight: bold;
floar: right;
}
nav ul {
list-style-type: none;
}
nav ul li {
float: left;
margin: 2px;
}
In less this becomes
nav {
font-size: 14px;
font-weight: bold;
floar: right;
ul {
list-style-type: none;
li {
float: left;
margin: 2px;
}
}
}
Adding an & lets you override the descendant and seemed to be called a combinator.
a {
color: blue;
&:hover {
color: green;
}
}
Other Features
Namespaces
Just add like C#
#my-namespace-name {
.set-button {
font-size: 14px;
}
}
To use it
#submit-button {
#my-form > .set-button;
}
Scope
We can scope variables
@size: 24px
#form {
@size: 18px;
...
}
String interpolation
@root: "/images/"
#form {
background: url("@{root}/background.png");
}
JavaScript
We can use back quotes to execute javascript
@root: "/images/";
@app-root:`"@{root}".toUpperCase()`;