indexBy

function Array.indexBy<T extends object, U extends PropertyKey>(
    target: readonly T[],
    by: (
        value: NoInfer<T>,
        idx: number,
        target: readonly NoInfer<T>[],
    ) => U,
): Record<U, T>

Creates a record by indexing the target array using the by function to generate keys. Optionally transforms values using the transform function.

Example

data-first

import { Array } from "@monstermann/array";

const users = [
    { id: 1, name: "Alice" },
    { id: 2, name: "Bob" },
];

Array.indexBy(users, (user) => user.id);
// { 1: { id: 1, name: 'Alice' }, 2: { id: 2, name: 'Bob' } }

Array.indexBy(
    users,
    (user) => user.id,
    (user) => user.name,
); // { 1: "Alice", 2: "Bob" }

data-last

import { Array } from "@monstermann/array";

pipe(
    users,
    Array.indexBy((user) => user.id),
); // { 1: { id: 1, name: 'Alice' }, 2: { id: 2, name: 'Bob' } }

pipe(
    users,
    Array.indexBy(
        (user) => user.id,
        (user) => user.name,
    ),
); // { 1: "Alice", 2: "Bob" }