# union()
The union method adds the given array to the collection. If the given array contains keys that are already in the original collection, the original collection's values will be preferred:
const collection = collect({
a: 'A',
b: 'B',
});
const union = collection.union({
a: 'AAA',
c: 'CCC',
b: 'BBB',
});
union.all();
// {
// a: 'A',
// b: 'B',
// c: 'CCC',
// }