@monstermann/fn/dist/map/reject.js

A utility library for TypeScript.

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

//#region src/map/reject.ts
/**
* `reject(map, by)`
*
* Rejects entries from `map` where `by` returns true for the value.
*
* ```ts
* reject(
*     new Map([
*         ["a", 1],
*         ["b", 2],
*         ["c", 3],
*     ]),
*     (value) => value > 1,
* ); // Map(1) { "a" => 1 }
* ```
*
* ```ts
* pipe(
*     new Map([
*         ["a", 1],
*         ["b", 2],
*         ["c", 3],
*     ]),
*     reject((value) => value > 1),
* ); // Map(1) { "a" => 1 }
* ```
*/
const reject = dfdlT((target, by) => {
	let result;
	for (const [key, value] of target) if (by(value, key, target)) {
		result ??= cloneMap(target);
		result.delete(key);
	}
	return result ?? target;
}, 2);

//#endregion
export { reject };