deno.land / std@0.166.0 / collections / distinct_by.ts

distinct_by.ts
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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
/** * Returns all elements in the given array that produce a distinct value using the given selector, preserving order by first occurrence * * Example: * * ```ts * import { distinctBy } from "https://deno.land/std@$STD_VERSION/collections/distinct_by.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts"; * * const names = [ 'Anna', 'Kim', 'Arnold', 'Kate' ] * const exampleNamesByFirstLetter = distinctBy(names, it => it.charAt(0)) * * assertEquals(exampleNamesByFirstLetter, [ 'Anna', 'Kim' ]) * ``` */export function distinctBy<T, D>( array: readonly T[], selector: (el: T) => D,): T[] { const selectedValues = new Set<D>(); const ret: T[] = [];
for (const element of array) { const currentSelectedValue = selector(element);
if (!selectedValues.has(currentSelectedValue)) { selectedValues.add(currentSelectedValue); ret.push(element); } }
return ret;}
std
Deno standard library
GitHub Repositorydenoland/deno_std
GitHub Stars
2458

Version Info

Tagged at
2 months ago