@monstermann/fn/dist/array/countBy.js

A utility library for TypeScript.

import { dfdlT } from "@monstermann/dfdl";

//#region src/array/countBy.ts
/**
* `countBy(target, predicate)`
*
* Counts the number of elements in the `target` array satisfy the provided `predicate` function.
*
* ```ts
* const isEven = (n) => n % 2 === 0;
* countBy([1, 2, 3, 4, 5], isEven); // 2
* ```
*
* ```ts
* const isEven = (n) => n % 2 === 0;
* pipe([1, 2, 3, 4, 5], countBy(isEven)); // 2
* ```
*/
const countBy = dfdlT((target, predicate) => {
	return target.reduce((acc, value, idx, target$1) => acc + (predicate(value, idx, target$1) ? 1 : 0), 0);
}, 2);

//#endregion
export { countBy };