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std/collections/map_keys.ts

Deno standard library
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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
/** * Applies the given transformer to all keys in the given record's entries and * returns a new record containing the transformed entries. * * If the transformed entries contain the same key multiple times, only the last * one will appear in the returned record. * * @example * ```ts * import { mapKeys } from "https://deno.land/std@$STD_VERSION/collections/map_keys.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts"; * * const counts = { a: 5, b: 3, c: 8 }; * * assertEquals( * mapKeys(counts, (it) => it.toUpperCase()), * { * A: 5, * B: 3, * C: 8, * }, * ); * ``` */export function mapKeys<T>( record: Readonly<Record<string, T>>, transformer: (key: string) => string,): Record<string, T> { const ret: Record<string, T> = {}; const keys = Object.keys(record);
for (const key of keys) { const mappedKey = transformer(key);
ret[mappedKey] = record[key]; }
return ret;}