Function groupBy

Collect the items of the iterator into a map of arrays keyed by the return value of your key generator function.

Optionally pass a map function which will map the inner values.

Note we return a Map which natively implements Symbol.iterator which means you are free to chain another operator after it’s consumed.

import { pipe } from "yta";
import { group-by, of } from "yta/sync";

pipe(
  of(
    { name: "foo", value: 5 },
    { name: "foo", value: 42 },
    { name: "bar", value: 101 },
    { name: "foo", value: 13 },
    { name: "bar", value: 2 },
  ),
  groupBy(
    ({ name }) => name,
    ({ value }) => value,
  ),
  Object.fromEntries,
);
// => { "foo": [5, 42, 13], "bar": [101, 2] }
Copy

See also:

The native Map object