Merge array by unique key

test.ts

const src = [
  { name: 'a', value: 1 },
  { name: 'b', value: 2 },
  { name: 'c', value: 3 },
];

const dst = [
  { name: 'd', value: 4 },
  { name: 'a', value: 5 },
  { name: 'f', value: 6 },
];

const reducer = (previous: any, current: any, index: number) => {
  if (index === 1) {
    return {
      [previous.name]: previous,
      [current.name]: current,
    };
  }
  return {
    ...previous,
    [current.name]: current,
  };
};

const r1 = dst.reduce(reducer);
const r2 = src.reduce(reducer);

console.log(Object.values({ ...r1, ...r2 }));

/*
[ { name: 'd', value: 4 },
  { name: 'a', value: 1 },
  { name: 'f', value: 6 },
  { name: 'b', value: 2 },
  { name: 'c', value: 3 } ]
*/