Vladimir Lisovets Vladimir Lisovets - 1 month ago 15
CSS Question

SASS : How to generate a map using a loop

My goal is to generate a SASS

to store variants of colors that are stored in the following map:

$colors : (

jet : #333333,
wintergreen-dream : #588C73,
eton-blue : #8FC0A9,
sunglow : #FFC33C,
light-kaki : #F2E394,
bege : #FAF3DD


So far, I am using a
to retrieve these variants:

@function light ($color, $val) { @return lighten($color, $val); }
@function dark ($color, $val) { @return darken($color, $val); }
@function transparent ($color, $val) { @return transparent($color, $val); }

The map I am expecting to be able to generate would look alike the following:

$colors-map : (

eton-blue : (

base : $eton-blue,
light : lighten($eton-blue, 15%),
dark : darken($eton-blue, 15%),
trans : transparent($eton-blue, .5)


jet : (

base : $jet,
light : lighten($jet, 15%),
dark : darken($jet, 15%),
trans : transparent($jet, .5)


// ...


Yet, the loop I've already tried to apply, looks like this:

@for $key, $value in $colors {}

However, I was naive to believe it could work inside of the map itself.

Questions which answers could easier answer this doubt :

  • How to add values to a SASS map (function), (key:value) ?

  • Basic usage of
    ? (
    @return map-merge($map, $new)

Strictly what I am looking for below :

$alternative-colors : (

@each $color, $hex in $colors {

#{$color} : (

light : lighten($color, 25%),
dark : darken($color, 25%)




But yet, it returns following error:

Error: Invalid CSS after \"...tive-colors : (\": expected \")\", was \"@each (...)

$colors : (
  jet                 : #333333,
  wintergreen-dream   : #588C73,
  eton-blue           : #8FC0A9,
  sunglow             : #FFC33C,
  light-kaki          : #F2E394,
  bege                : #FAF3DD

$colors-map: ();

@function create_colour_map($color, $percentage, $opacity) {
  $map: (
    base: $color,
    light: lighten($color, $value),
    dark: darken($color, $value),
    trans: transparentize($color, $opacity)
  @return $map;

@each $key, $value in $colors {
  $map: ();
  $map: map-merge($map, ($key: create_colour_map($value, 15%, 0.5)) );
  $colors-map: map-merge($colors-map, $map);

@debug $colors-map; //prints out the map below 
  (jet:               (base: #333333, 
                       light: #595959,
                       dark: #0d0d0d,
                       trans: rgba(51, 51, 51, 0.5)), 
   wintergreen-dream: (base: #588C73, 
                       light: #81b099,
                       dark: #3a5d4c,
                       trans: rgba(88, 140, 115, 0.5)),
   eton-blue:          (base: #8FC0A9,
                        light: #c0dccf,
                        dark: #5ea483,
                        trans: rgba(143, 192, 169, 0.5)), 
   sunglow:            (base: #FFC33C,
                        light: #ffdb89,
                        dark: #efa500,
                        trans: rgba(255, 195, 60, 0.5)),
   light-kaki:         (base: #F2E394,
                        light: #faf5d8,
                        dark: #ead150,
                        trans: rgba(242, 227, 148, 0.5)),
   bege:               (base: #FAF3DD,
                        light: white,
                        dark: #f0db9a,
                        trans: rgba(250, 243, 221, 0.5)))

I merged your three functions into one, the create_colour_map function. It takes three arguments for the colour, percentage and opacity. The function returns a map

Calling the create_colour_map(#333333, 15%, 0.5) with those args returns a map

(base: #333333, 
 light: #595959,
 dark: #0d0d0d,
 trans: rgba(51, 51, 51, 0.5)

I just loop through the $colors map and each time call the function which generates a map that becomes the value of the key each time for an iteration.

How to add values to a map and basic usage of map-merge?

I use map-merge to add values to a map. Just as the name implies, it joins two maps together and since it is a function, it can be used where Sass expects a value. So take for example the code below

$map: ( colour: red);
$new_map: (class: blue);

If we wanted $map to have the same keys and values as both maps, we could write

$map: map-merge( $map, $new_map); // $map: (colour: red, class: blue)

This is basically saying the return value of the function ( which would be the two maps joined together ) is the value of $map

Simply put just think of that line of code as variable reassignment in programming languages. This is how you can use map-merge to set values in maps. The 2nd argument for the map-merge method doesn't need to be a predefined map variable. It could have been written this way

$map: map-merge( $map, (class: blue) );

So here it just looks like you're adding a new key and value to the $map variable