Merge object data with same date

I have the following array I need help with.

let test = [
{
  date: ["2021-11-09", "2021-11-09", "2021-11-10", "2021-11-10"],
  amount: [0.5, 0.5, 1, 2],
}];

How can I merge the amounts that have the same date? I want the data to be returned as below:

date: ["2021-11-09", "2021-11-10"],
amount: [1, 3],

Thank you in advance!

>Solution :

As mentioned in the comments, this is just a ‘group by’ by date from the date array, summing the elements at the same index in the amount array.

let test = [
  {
    date: ['2021-11-09', '2021-11-09', '2021-11-10', '2021-11-10'],
    amount: [0.5, 0.5, 1, 2],
  },
];

const result = test.map(({ date, amount }) => {
  const grouped = date.reduce((a, d, i) => a.set(d, (a.get(d) ?? 0) + amount[i]), new Map());

  return {
    date: [...grouped.keys()],
    amount: [...grouped.values()],
  };
});

console.log(result);

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