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first_not_nullish_of.ts
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first_not_nullish_of.ts
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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
/**
* Applies the given selector to elements in the given array until a value is produced that is neither `null` nor `undefined` and returns that value
* Returns `undefined` if no such value is produced
*
* Example:
*
* ```ts
* import { firstNotNullishOf } from "https://deno.land/std@$STD_VERSION/collections/first_not_nullish_of.ts";
* import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts";
*
* const tables = [
* { number: 11, order: null },
* { number: 12, order: 'Soup' },
* { number: 13, order: 'Salad' },
* ]
* const nextOrder = firstNotNullishOf(tables, it => it.order)
*
* assertEquals(nextOrder, 'Soup')
* ```
*/
export function firstNotNullishOf<T, O>(
array: readonly T[],
selector: (item: T) => O | undefined | null,
): NonNullable<O> | undefined {
for (const current of array) {
const selected = selector(current);
if (selected !== null && selected !== undefined) {
return selected as NonNullable<O>;
}
}
return undefined;
}