Variables in parameters in SASS

There are situations where a mixin or function needs to take an unknown number of parameters. That's why SASS has the ability to pass "variable parameters," or parameters that are specified last in a function or mixin and pack all other passed parameters into a list.

After such parameters, you need to put an ellipsis. Consider the following example:

@mixin box-content-padding($padding...) {
	-moz-box-content-padding: $padding;
	-webkit-box-content-padding: $padding;
}
div {
	@include box-content-padding(0px 4px 5px 2px);
}

Compilation result:

div {
	-moz-box-content-padding: 0px 4px 5px 2px;
	-webkit-box-content-padding: 0px 4px 5px 2px;
}

You can also pass named parameters to variables of a function or mixin. To access them, use the keywords($args) function, which returns them as a mapping of names (without the $ sign) to values.

@mixin common-colors($text-color, $background, $shadow) {
	color: $text-color;
	background-color: $background;
	box-shadow: $shadow;
}

$values: white, green, grey;

.primary {
	@include common-colors($values...);
}

$value-map: (text-color: black, background: grey, shadow: green);

.secondary {
	@include common-colors($value-map...);
}

After compilation we will see:

.primary {
	color: white;
	background-color: green;
	box-shadow: grey;
}

.secondary {
	color: black;
	background-color: grey;
	box-shadow: green;
}