Vielzeug

Appearance

union ​

Problem ​

You need to merge two arrays and deduplicate — for example combining two tag lists without duplicates.

Solution ​

Use union(source, other, selector?) to return items from both arrays with duplicates removed.

ts
import { union } from '@vielzeug/arsenal';

union([1, 2, 3], [2, 3, 4, 5]);
// [1, 2, 3, 4, 5]

const a = [{ id: 1 }, { id: 2 }];
const b = [{ id: 2 }, { id: 3 }];
union(a, b, (u) => u.id);
// [{ id: 1 }, { id: 2 }, { id: 3 }]

Pitfalls ​

  • Result order: source items first, then unique items from other.
  • Without a selector, uses deep equality.