API reference / @evolu/common / Array / partitionArray

Function: partitionArray()

Defined in: packages/common/src/Array.ts:344

Partitions an array into two arrays based on a predicate or refinement function.

Returns a tuple where the first array contains elements that satisfy the predicate, and the second array contains elements that do not. Accepts both mutable and readonly arrays.

When used with a refinement function (with value is Type syntax), TypeScript will narrow the first array to the narrowed type, making it useful for filtering with Evolu Types like PositiveInt.is.

Examples

With predicate

const [evens, odds] = partitionArray([1, 2, 3, 4, 5], (x) => x % 2 === 0);
evens; // [2, 4]
odds; // [1, 3, 5]

With refinement

const mixed: ReadonlyArray<NonEmptyString | PositiveInt> = [
  NonEmptyString.orThrow("hello"),
  PositiveInt.orThrow(42),
];
const [positiveInts, strings] = partitionArray(mixed, PositiveInt.is);
// positiveInts: ReadonlyArray<PositiveInt> (narrowed type)
// strings: ReadonlyArray<NonEmptyString> (Exclude<T, PositiveInt>)

Type Parameters

Type Parameter
`T`
`S`

Parameters

Parameter	Type
`array`	readonly `T`[]
`refinement`	`RefinementWithIndex`<`T`, `S`>

Returns

readonly [readonly S[], readonly Exclude<T, S>[]]

Defined in: packages/common/src/Array.ts:348