sass:list

{% render 'doc_snippets/built-in-module-status' %}

{% funFact %} In Sass, every map counts as a list that contains a two-element list for each key/value pair. For example, (1: 2, 3: 4) counts as (1 2, 3 4). So all these functions work for maps as well!

Individual values also count as lists. All these functions treat 1px as a list that contains the value 1px. {% endfunFact %}

{% function 'list.append($list, $val, $separator: auto)', 'append($list, $val, $separator: auto)', 'returns:list' %} Returns a copy of $list with $val added to the end.

If $separator is comma, space, or slash, the returned list is comma-separated, space-separated, or slash-separated, respectively. If it's auto (the default), the returned list will use the same separator as $list (or space if $list doesn't have a separator). Other values aren't allowed.

Note that unlike list.join(), if $val is a list it's nested within the returned list rather than having all its elements added to the returned list.

{% codeExample 'list-append' %} @use 'sass:list';

@debug list.append(10px 20px, 30px); // 10px 20px 30px
@debug list.append((blue, red), green); // blue, red, green
@debug list.append(10px 20px, 30px 40px); // 10px 20px (30px 40px)
@debug list.append(10px, 20px, $separator: comma); // 10px, 20px
@debug list.append((blue, red), green, $separator: space); // blue red green
===
@use 'sass:list'

@debug list.append(10px 20px, 30px)  // 10px 20px 30px
@debug list.append((blue, red), green)  // blue, red, green
@debug list.append(10px 20px, 30px 40px)  // 10px 20px (30px 40px)
@debug list.append(10px, 20px, $separator: comma)  // 10px, 20px
@debug list.append((blue, red), green, $separator: space)  // blue red green

{% endcodeExample %} {% endfunction %}

{% function 'list.index($list, $value)', 'index($list, $value)', 'returns:number | null' %} Returns the index of $value in $list.

If $value doesn't appear in $list, this returns null. If $value appears multiple times in $list, this returns the index of its first appearance.

{% render 'code_snippets/example-list-index' %} {% endfunction %}

{% function 'list.is-bracketed($list)', 'is-bracketed($list)', 'returns:boolean' %} Returns whether $list has square brackets.

{% codeExample 'list-is-bracketed' %} @use 'sass:list';

@debug list.is-bracketed(1px 2px 3px); // false
@debug list.is-bracketed([1px, 2px, 3px]); // true
===
@use 'sass:list'

@debug list.is-bracketed(1px 2px 3px)  // false
@debug list.is-bracketed([1px, 2px, 3px])  // true

{% endcodeExample %} {% endfunction %}

{% function 'list.join($list1, $list2, $separator: auto, $bracketed: auto)', 'join($list1, $list2, $separator: auto, $bracketed: auto)', 'returns:list' %} Returns a new list containing the elements of $list1 followed by the elements of $list2.

{% headsUp %} Because individual values count as single-element lists, it's possible to use list.join() to add a value to the end of a list. However, this is not recommended, since if that value is a list it will be concatenated, which is probably not what you're expecting.

Use [`list.append()`](#append) instead to add a single value to a list. Only
use `list.join()` to combine two lists together into one.

{% endheadsUp %}

If $separator is comma, space, or slash, the returned list is comma-separated, space-separated, or slash-separated, respectively. If it's auto (the default), the returned list will use the same separator as $list1 if it has a separator, or else $list2 if it has a separator, or else space. Other values aren't allowed.

If $bracketed is auto (the default), the returned list will be bracketed if $list1 is. Otherwise, the returned list will have square brackets if $bracketed is truthy and no brackets if $bracketed is falsey.

{% codeExample 'list-join' %} @use 'sass:list';

@debug list.join(10px 20px, 30px 40px); // 10px 20px 30px 40px
@debug list.join((blue, red), (#abc, #def)); // blue, red, #abc, #def
@debug list.join(10px, 20px); // 10px 20px
@debug list.join(10px, 20px, $separator: comma); // 10px, 20px
@debug list.join((blue, red), (#abc, #def), $separator: space); // blue red #abc #def
@debug list.join([10px], 20px); // [10px 20px]
@debug list.join(10px, 20px, $bracketed: true); // [10px 20px]
===
@use 'sass:list'

@debug list.join(10px 20px, 30px 40px)  // 10px 20px 30px 40px
@debug list.join((blue, red), (#abc, #def))  // blue, red, #abc, #def
@debug list.join(10px, 20px)  // 10px 20px
@debug list.join(10px, 20px, comma)  // 10px, 20px
@debug list.join((blue, red), (#abc, #def), space)  // blue red #abc #def
@debug list.join([10px], 20px)  // [10px 20px]
@debug list.join(10px, 20px, $bracketed: true)  // [10px 20px]

{% endcodeExample %} {% endfunction %}

{% function 'list.length($list)', 'length($list)', 'returns:number' %} Returns the length of $list.

This can also return the number of pairs in a map.

{% codeExample 'list-length' %} @use 'sass:list';

@debug list.length(10px); // 1
@debug list.length(10px 20px 30px); // 3
@debug list.length((width: 10px, height: 20px)); // 2
===
@use 'sass:list'

@debug list.length(10px)  // 1
@debug list.length(10px 20px 30px)  // 3
@debug list.length((width: 10px, height: 20px))  // 2

{% endcodeExample %} {% endfunction %}

{% function 'list.separator($list)', 'list-separator($list)', 'returns:unquoted string' %} Returns the name of the separator used by $list, either space, comma, or slash.

If $list doesn't have a separator, returns space.

{% codeExample 'list-separator' %} @use 'sass:list';

@debug list.separator(1px 2px 3px); // space
@debug list.separator((1px, 2px, 3px)); // comma
@debug list.separator('Helvetica'); // space
@debug list.separator(()); // space
===
@use 'sass:list'

@debug list.separator(1px 2px 3px)  // space
@debug list.separator((1px, 2px, 3px))  // comma
@debug list.separator('Helvetica')  // space
@debug list.separator(())  // space

{% endcodeExample %} {% endfunction %}

{% function 'list.nth($list, $n)', 'nth($list, $n)' %} Returns the element of $list at index $n.

If $n is negative, it counts from the end of $list. Throws an error if there is no element at index $n.

{% render 'code_snippets/example-list-nth' %} {% endfunction %}

{% function 'list.set-nth($list, $n, $value)', 'set-nth($list, $n, $value)', 'returns:list' %} Returns a copy of $list with the element at index $n replaced with $value.

If $n is negative, it counts from the end of $list. Throws an error if there is no existing element at index $n.

{% codeExample 'list-set-nth' %} @use 'sass:list';

@debug list.set-nth(10px 20px 30px, 1, 2em); // 2em 20px 30px
@debug list.set-nth(10px 20px 30px, -1, 8em); // 10px, 20px, 8em
@debug list.set-nth((Helvetica, Arial, sans-serif), 3, Roboto); // Helvetica, Arial, Roboto
===
@use 'sass:list'

@debug list.set-nth(10px 20px 30px, 1, 2em); // 2em 20px 30px
@debug list.set-nth(10px 20px 30px, -1, 8em); // 10px, 20px, 8em
@debug list.set-nth((Helvetica, Arial, sans-serif), 3, Roboto); // Helvetica, Arial, Roboto

{% endcodeExample %} {% endfunction %}

{% function 'list.slash($elements...)', 'returns:list' %} Returns a slash-separated list that contains $elements.

{% headsUp %} This function is a temporary solution for creating slash-separated lists. Eventually, they'll be written literally with slashes, as in 1px / 2px / solid, but for the time being [slashes are used for division] so Sass can't use them for new syntax until the old syntax is removed.

[slashes are used for division]: /documentation/breaking-changes/slash-div

{% endheadsUp %}

{% codeExample 'list-slash' %} @use 'sass:list';

@debug list.slash(1px, 50px, 100px); // 1px / 50px / 100px
===
@use 'sass:list'

@debug list.slash(1px, 50px, 100px)  // 1px / 50px / 100px

{% endcodeExample %} {% endfunction %}

{% function 'list.zip($lists...)', 'zip($lists...)', 'returns:list' %} Combines every list in $lists into a single list of sub-lists.

Each element in the returned list contains all the elements at that position in $lists. The returned list is as long as the shortest list in $lists.

The returned list is always comma-separated and the sub-lists are always space-separated.

{% codeExample 'list-zip' %} @use 'sass:list';

@debug list.zip(10px 50px 100px, short mid long); // 10px short, 50px mid, 100px long
@debug list.zip(10px 50px 100px, short mid); // 10px short, 50px mid
===
@use 'sass:list'

@debug list.zip(10px 50px 100px, short mid long)  // 10px short, 50px mid, 100px long
@debug list.zip(10px 50px 100px, short mid)  // 10px short, 50px mid

{% endcodeExample %} {% endfunction %}