JavaScript: Merging dictionaries

dictionary.js

Implement and export as default a function that merges several dictionaries (objects) into a single dictionary. The function takes any number of arguments and returns an object in which each key contains a list of unique values as an array. The items in the list are arranged in the order in which they appear in the given dictionaries.

Examples:

merge({}, {}, {});
// {}

merge({ a: 1, b: 2 }, { a: 3 });
// { a: [1, 3], b: [2] }

merge(
    { a: 1, b: 2, c: 3 },
    {},
    { a: 3, b: 2, d: 5 },
    { a: 6 },
    { b: 4, c: 3, d: 2 },
    { e: 9 },
  );
// { a: [1, 3, 6], b: [2, 4], c: [3], d: [5, 2], e: [9] }