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std/collections/intersect.ts

Deno standard library
denoland/deno_std
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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import { filterInPlace } from "./_utils.ts";
/** * Returns all distinct elements that appear at least once in each of the given * arrays. * * @example * ```ts * import { intersect } from "https://deno.land/std@$STD_VERSION/collections/intersect.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts"; * * const lisaInterests = ["Cooking", "Music", "Hiking"]; * const kimInterests = ["Music", "Tennis", "Cooking"]; * const commonInterests = intersect(lisaInterests, kimInterests); * * assertEquals(commonInterests, ["Cooking", "Music"]); * ``` */export function intersect<T>(...arrays: (readonly T[])[]): T[] {  const [originalHead, ...tail] = arrays;  const head = [...new Set(originalHead)];  const tailSets = tail.map((it) => new Set(it));
  for (const set of tailSets) {    filterInPlace(head, (it) => set.has(it));    if (head.length === 0) return head;  }
  return head;}