@nullvoxpopuli/ember-composable-helpers/src/helpers/union.ts

Composable helpers for Ember

import { helper } from '@ember/component/helper';
import asArray from '../utils/as-array.ts';

export function union([...arrays]) {
  const items = [].concat(...arrays);

  return items.filter(
    (value, index, array) => asArray(array).indexOf(value) === index,
  );
}

export default helper(union);