Javascript 从另一个数组中的对应行键值对更新数组中的键值对对象

const map = array2.reduce((r, e) => ((r[e.key1] ??= {})[e.key2] = e, r), {});

array1.forEach(e => {
  const found = map[e.key1]?.[e.key2];
  if(!found) return;
  for(const year in e.years){
    e.years[year] -= found.years[year]??0;
  }
});

console.log(array1);

<script>

const array1 = [{"key1":"A","key2":"Fred","years":{"2013":16,"2014":11,"2015":17}},{"key1":"A","key2":"Jim","years":{"2013":1,"2014":4,"2015":3}},{"key1":"B","key2":"Mary","years":{"2013":1,"2014":4,"2015":3}}]
const array2 = [{"key1":"A","key2":"Fred","years":{"2013":3,"2014":2,"2015":7}},{"key1":"A","key2":"Jim","years":{"2013":9,"2014":3,"2015":1}},{"key1":"B","key2":"Mary","years":{"2013":8,"2014":3,"2015":6}}]

</script>

 let array2 = [
    {
        "key1": "A",
        "key2": "Fred",
        key3: 1,
        "years": {
            "2013": 16,
            "2014": 11,
            "2015": 17
        }
    },
    {
        "key1": "A",
        "key2": "Jim",
        key3: 2,
        "years": {
            "2013": 1,
            "2014": 4,
            "2015": 3
        }
    },
    {
        "key1": "B",
        "key2": "Mary",
        key3: 3,
        "years": {
            "2013": 1,
            "2014": 4,
            "2015": 3
        }
    }
]
 
const map = array2.reduce((r, e) => (((r[e.key1] ??= {})[e.key2] ??= {})[e.key3] = e, r), {});

console.log(map);

const keys = [...Array(3000).fill().keys()];
keys.forEach((k, i) => {
  const idx = Math.random()*(keys.length-i)|0 + i;
  [keys[i], keys[idx]] = [keys[idx], k];
});
let idx = 0;
const $chunk = () => [{"key1":"A","key2":keys[idx++],"years":{"2013":16,"2014":11,"2015":17}},{"key1":"A","key2":keys[idx++],"years":{"2013":1,"2014":4,"2015":3}},{"key1":"B","key2":keys[idx++],"years":{"2013":1,"2014":4,"2015":3}}]
const array2 = [{"key1":"A","key2":1,"years":{"2013":3,"2014":2,"2015":7}},{"key1":"A","key2":2, "years":{"2013":9,"2014":3,"2015":1}},{"key1":"B","key2":3,"years":{"2013":8,"2014":3,"2015":6}}]

const $input = [];
const array1 = $input;

// @benchmark Andrew Parks

array1.forEach(({key1, key2, years}) => Object.entries(
    array2.find(({key1: a, key2: b}) => a===key1 && b===key2)?.years ?? {}
  ).forEach(([year, count]) => years[year] -= count)
)
array1;

// @benchmark Onur Dogan

array1.concat(array2).reduce((tot, val) => { 
const index = tot.findIndex(({ key1, key2 }) => key1 === val.key1 && key2 === val.key2);

if(index > -1){
  Object.keys(val.years).forEach(yearKey => {
    tot[index].years[yearKey] -= val.years[yearKey];
  });
}
else {
    tot.push(val);
}

   return tot;
}, []);

// @benchmark Alexander

const map = array2.reduce((r, e) => ((r[e.key1] ??= {})[e.key2] = e, r), {});

array1.forEach(e => {
  const found = map[e.key1]?.[e.key2];
  if(!found) return;
  for(const year in e.years){
    e.years[year] -= found.years[year]??0;
  }
});
array1;

/*@end*/eval(atob('e2xldCBlPWRvY3VtZW50LmJvZHkucXVlcnlTZWxlY3Rvcigic2NyaXB0Iik7aWYoIWUubWF0Y2hlcygiW2JlbmNobWFya10iKSl7bGV0IHQ9ZG9jdW1lbnQuY3JlYXRlRWxlbWVudCgic2NyaXB0Iik7dC5zcmM9Imh0dHBzOi8vY2RuLmpzZGVsaXZyLm5ldC9naC9zaWxlbnRtYW50cmEvYmVuY2htYXJrL2xvYWRlci5qcyIsdC5kZWZlcj0hMCxkb2N1bWVudC5oZWFkLmFwcGVuZENoaWxkKHQpfX0='));