Transformations

import {
  unique,
  uniqueBy,
  flat,
  inGroups,
  inGroupsOf,
  occurrences,
  compact,
  compactNullish,
} from 'op-array/transformations';

unique(values)

unique([1, 2, 2, 3, 1]); // [1, 2, 3]

uniqueBy(values, key)

Dedupes by the value at key (dot-delimited for nested paths). First occurrence per resolved key wins, preserving order. Items missing the path collapse to a single undefined bucket. Empty input returns [].

uniqueBy(users, 'id');
uniqueBy(orders, 'customer.email');

flat(values, depth = 1)

Mirrors native Array.prototype.flat while accepting readonly inputs.

flat([[1, 2], [3, [4]]]);   // [1, 2, 3, [4]]
flat([[1, [2, [3]]]], 2);   // [1, 2, [3]]

inGroups(values, groupCount)

Splits into exactly groupCount contiguous groups. Throws RangeError on a non-positive groupCount.

inGroups([1, 2, 3, 4, 5], 2); // [[1, 2, 3], [4, 5]]
inGroups([1, 2, 3], 5);       // [[1], [2], [3], [], []]

inGroupsOf(values, size)

Splits into groups of size consecutive elements. Throws RangeError on a non-positive size.

inGroupsOf([1, 2, 3, 4, 5], 2); // [[1, 2], [3, 4], [5]]

occurrences(values)

occurrences([1, 2, 2, 3]); // [[1, 1], [2, 2], [3, 1]]

compact(values)

Removes all falsy values: false, 0, 0n, '', null, undefined, NaN. Mirrors lodash.compact.

compact([0, 1, false, 2, '', 3, null, NaN]); // [1, 2, 3]

compactNullish(values)

Removes only null / undefined.

compactNullish([0, 1, null, '', undefined]); // [0, 1, '']