arr1 = [{3265: {…}}, {3266: {…}}]
arr2 = [{3265: {…}}, {3267: {…}}]
result = [{3265: {…}}, {3266: {…}}, {3267: {…}}]
const result = Object
.entries(Object.assign({}, ...arr1, ...arr2))
.map(n => ({ [n[0]]: n[1] }));
const union = (key, ...arrs) =>
Object.values([].concat(...arrs).reduce((acc, n) => (acc[key(n)] = n, acc), {}));
const result = union(el => Object.keys(el)[0], arr1, arr2);
const result = _.unionBy(arr1, arr2, el => _.keys(el)[0]);