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Function: flatMap()

flatMap<ElementType, MappedType>(iterable: IterableResolvable<ElementType>, callbackFn: (element: ElementType, index: number) => IterableResolvable<MappedType>): IterableIterator<MappedType>

Creates an iterable that yields the elements of each iterable returned by the provided function on each element of the input iterable.

Type parameters

Type parameter
ElementType
MappedType

Parameters

ParameterTypeDescription
iterableIterableResolvable<ElementType>An iterator to map.
callbackFn(element: ElementType, index: number) => IterableResolvable<MappedType>A function to execute for each element produced by the iterator. It should return an iterator or iterable that yields elements to be yielded by flatMap(), or a single non-iterator/iterable value to be yielded.

Returns

IterableIterator<MappedType>

An iterator that applies a function to each element of the input iterator and yields the results.

Example

import { flatMap } from '@sapphire/iterator-utilities';

const iterable = [1, 2, 3];
console.log([...flatMap(iterable, (value) => [value, value * 2])]);
// Output: [1, 2, 2, 4, 3, 6]

Source

projects/utilities/packages/iterator-utilities/src/lib/flatMap.ts:21