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

A utility library for TypeScript.

import { is } from "../function/is.js";
import { dfdlT } from "@monstermann/dfdl";
import { cloneArray } from "@monstermann/remmi";

//#region src/array/replaceLastOrElse.ts
/**
* `replaceLastOrElse(target, value, replacement, orElse)`
*
* Replaces the last occurrence of `value` in `target` with `replacement`. If `value` is not found, calls `orElse` with the original array.
*
* ```ts
* replaceLastOrElse([1, 2, 3, 2], 2, 9, () => []); // [1, 2, 3, 9]
* replaceLastOrElse([1, 2, 3], 4, 9, (arr) => arr); // [1, 2, 3]
* ```
*
* ```ts
* pipe(
*     [1, 2, 3, 2],
*     replaceLastOrElse(2, 9, () => []),
* ); // [1, 2, 3, 9]
* pipe(
*     [1, 2, 3],
*     replaceLastOrElse(4, 9, (arr) => arr),
* ); // [1, 2, 3]
* ```
*/
const replaceLastOrElse = dfdlT((target, value, replacement, orElse) => {
	if (is(value, replacement)) return target;
	const idx = target.lastIndexOf(value);
	if (idx === -1) return orElse(target);
	const result = cloneArray(target);
	result.splice(idx, 1, replacement);
	return result;
}, 4);

//#endregion
export { replaceLastOrElse };