arrays
In Filters
Array-manipulation filters for Eleventy. Nunjucks & Liquid have native
first / last / reverse filters, but 11ty.js (JavaScript) templates &
Handlebars do not. Registering these via dashly makes them available in all
four, as checked by test/engines.test.js.
import {
first,
last,
reverse,
groupBy,
sortBy,
chunk,
where,
pluck,
} from '@allons-y/dashly/filters/arrays';first(value, n?)
Return the first item of an array, or the first n items if a count is
supplied. With no count, matches Nunjucks first (single item). With a
count, returns the first N items — covers the "limit / head" use case.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
value
|
readonly T[] |
||
n
(optional)
|
number |
Returns
T | T[] | undefined
Examples
// 'a'
first(['a', 'b', 'c']);// ['a', 'b']
first(['a', 'b', 'c'], 2);{{ collections.posts | first }}{% for post in collections.posts | first(3) %} … {% endfor %}last(value, n?)
Return the last item of an array, or the last n items if a count is
supplied. Mirror of first.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
value
|
readonly T[] |
||
n
(optional)
|
number |
Returns
T | T[] | undefined
Examples
// 'c'
last(['a', 'b', 'c']);// ['b', 'c']
last(['a', 'b', 'c'], 2);{{ collections.posts | last }}reverse(value)
Reverse an array or a string without mutating the input.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
value
|
readonly T[] | string |
Returns
T[] | string
Examples
// [3, 2, 1]
reverse([1, 2, 3]);// 'cba'
reverse('abc');{{ collections.posts | reverse }}groupBy(value, keyOrFn)
Group array items by a key, a dot-path, or a function. Returns a plain object keyed by the grouping value, with each value an array of items.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
value
|
readonly T[] |
||
keyOrFn
|
string | ((item: T) => unknown) |
Property name (dot-paths supported, e.g. 'data.year') or selector function. |
Returns
Record<string, T[]>
Examples
// { 2025: [...], 2026: [...] }
groupBy(posts, 'data.year');groupBy(posts, (p) => p.data.tags[0]);{% for year, items in collections.posts | groupBy('data.year') %} … {% endfor %}sortBy(value, keyOrFn, order?)
Sort an array by a key, dot-path, or selector function, without mutating
the input. String values are compared with localeCompare; everything else
with standard < / >.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
value
|
readonly T[] |
||
keyOrFn
|
string | ((item: T) => unknown) |
||
order
(optional)
|
'asc' | 'desc' |
'asc' |
Returns
T[]
Examples
sortBy(posts, 'data.date', 'desc');sortBy(items, (item) => item.priority);chunk(value, size)
Split an array into N-sized chunks. The final chunk may be smaller than
size. Returns an empty array for non-array or invalid-size input.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
value
|
readonly T[] |
||
size
|
number |
Returns
T[][]
Examples
// [[1, 2], [3, 4], [5]]
chunk([1, 2, 3, 4, 5], 2);{# render a gallery grid #}
{% for row in images | chunk(3) %} … {% endfor %}where(value, keyOrFn, expected?)
Filter an array by a key/dot-path equality check. When expected is
omitted, items where the keyed value is truthy are kept (useful for
where(posts, 'data.featured')).
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
value
|
readonly T[] |
||
keyOrFn
|
string | ((item: T) => unknown) |
||
expected
(optional)
|
unknown |
Returns
T[]
Examples
where(posts, 'data.draft', false);where(posts, 'data.featured'); // truthy-onlypluck(value, keyOrFn)
Project an array of objects onto a single key or dot-path.
Parameters
| Name | Type | Default | Description |
|---|---|---|---|
value
|
readonly T[] |
||
keyOrFn
|
string | ((item: T) => unknown) |
Returns
unknown[]
Examples
// ['Hello', 'World']
pluck([{ title: 'Hello' }, { title: 'World' }], 'title');{{ collections.posts | pluck('data.title') | join(', ') }}