/
map_not_nullish.ts
40 lines (36 loc) · 1.17 KB
/
map_not_nullish.ts
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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
/**
* Returns a new array, containing all elements in the given array transformed using the given transformer, except the ones
* that were transformed to `null` or `undefined`
*
* Example:
*
* ```ts
* import { mapNotNullish } from "https://deno.land/std@$STD_VERSION/collections/map_not_nullish.ts";
* import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts";
*
* const people = [
* { middleName: null },
* { middleName: 'William' },
* { middleName: undefined },
* { middleName: 'Martha' },
* ]
* const foundMiddleNames = mapNotNullish(people, it => it.middleName)
*
* assertEquals(foundMiddleNames, [ 'William', 'Martha' ])
* ```
*/
export function mapNotNullish<T, O>(
array: readonly T[],
transformer: (el: T) => O,
): NonNullable<O>[] {
const ret: NonNullable<O>[] = [];
for (const element of array) {
const transformedElement = transformer(element);
if (transformedElement !== undefined && transformedElement !== null) {
ret.push(transformedElement as NonNullable<O>);
}
}
return ret;
}