@monstermann/fn/dist/set/union.js

A utility library for TypeScript.

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

//#region src/set/union.ts
/**
* `union(target, source)`
*
* Returns a new set containing all unique values from both the `target` set and the `source` set.
*
* ```ts
* union(new Set([1, 2]), new Set([2, 3, 4])); // Set([1, 2, 3, 4])
* union(new Set([1, 2]), new Set([3, 4])); // Set([1, 2, 3, 4])
* ```
*
* ```ts
* pipe(new Set([1, 2]), union(new Set([2, 3, 4]))); // Set([1, 2, 3, 4])
* pipe(new Set([1, 2]), union(new Set([3, 4]))); // Set([1, 2, 3, 4])
* ```
*/
const union = dfdlT((target, source) => {
	if (source.size === 0) return target;
	if (target.size === 0) return source;
	for (const element of source) if (!target.has(element)) {
		const result = /* @__PURE__ */ new Set();
		for (const a of target) result.add(a);
		for (const b of source) result.add(b);
		return result;
	}
	return target;
}, 2);

//#endregion
export { union };