Split Object to array of objects

I want to separate the object below into two objects following the year in the keys.

const a = {
  "id": "2",
  "2019_progrSin": "2",
  "2019_percResponsabilita": "30",
  "2019_flag": "B",
  "2019_tipoResponsabilitaSinistro": "O",
  "2019_anno": "2019",
  "2019_codComp": "O",
  "2018_progrSin": "2",
  "2018_percResponsabilita": "50",
  "2018_flag": "Y",
  "2018_tipoResponsabilitaSinistro": "I",
  "2018_anno": "2018",
  "2018_codComp": "O"
}

I want obtain b from a, like:

const b = [
 {
   "2019_progrSin": "2",
   "2019_percResponsabilita": "30",
   "2019_flag": "B",
   "2019_tipoResponsabilitaSinistro": "O",
   "2019_anno": "2019",
   "2019_codComp": "O",
 },
 {
   "2018_progrSin": "2",
   "2018_percResponsabilita": "50",
   "2018_flag": "Y",
   "2018_tipoResponsabilitaSinistro": "I",
   "2018_anno": "2018",
   "2018_codComp": "O"
 }
]

The property can be more. ( like "2017_flag" / "2016_flag" and so on)

>Solution :

Using Array.prototype.reduce, Object.values, and Object.entries. This would also work:

const input = {
  id: "2",
  "2019_progrSin": "2",
  "2019_percResponsabilita": "30",
  "2019_flag": "B",
  "2019_tipoResponsabilitaSinistro": "O",
  "2019_anno": "2019",
  "2019_codComp": "O",
  "2018_progrSin": "2",
  "2018_percResponsabilita": "50",
  "2018_flag": "Y",
  "2018_tipoResponsabilitaSinistro": "I",
  "2018_anno": "2018",
  "2018_codComp": "O",
};

const output = Object.values(
  Object.entries(input).reduce((prev, [key, value]) => {
    const [year] = key.split("_");
    if (!isNaN(year)) {
      if (!prev[year]) {
        prev[year] = {};
      }
      prev[year][key] = value;
    }
    return prev;
  }, {})
);

console.log(output);