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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
/** * Transforms the given array into a Record, extracting the key of each element using the given selector. * If the selector produces the same key for multiple elements, the latest one will be used (overriding the * ones before it). * * Example: * * ```ts * import { associateBy } from "https://deno.land/std@$STD_VERSION/collections/mod.ts" * import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts"; * * const users = [ * { id: 'a2e', userName: 'Anna' }, * { id: '5f8', userName: 'Arnold' }, * { id: 'd2c', userName: 'Kim' }, * ] * const usersById = associateBy(users, it => it.id) * * assertEquals(usersById, { * 'a2e': { id: 'a2e', userName: 'Anna' }, * '5f8': { id: '5f8', userName: 'Arnold' }, * 'd2c': { id: 'd2c', userName: 'Kim' }, * }) * ``` */export function associateBy<T>( array: readonly T[], selector: (el: T) => string,): Record<string, T> { const ret: Record<string, T> = {};
for (const element of array) { const selectedValue = selector(element);
ret[selectedValue] = element; }
return ret;}