reducing array of objects to sum up for multiple properties

Question

I am having array of objects where i want to reduce the array and get the count of two properties. When my array length is more than one it works but when its one or less it doesn't

const data = [{id: 1, count:3 , alt_count: 2}, {id: 2, count:4 , alt_count: 5}];
const countObj = data.reduce((acc, curr) => {
      return {
        count_total: acc.count + curr.count,
        alt_count_total: acc.alt_count + curr.alt_count,
      };
    });
 console.log(countObj) // giving me both count_total and alt_count_total

But here its not giving me, instead it gives me the same object

const data = [{id: 1, count:3 , alt_count: 2}];
const countObj = data.reduce((acc, curr) => {
          return {
            count_total: acc.count + curr.count,
            alt_count_total: acc.alt_count + curr.alt_count,
          };
        });
console.log(countObj) // giving me entire first object

Any help is appreciated

Chandrashekhar Kase · Accepted Answer · 2023-04-10 05:17:36Z

3

You need to provide the initial value to reduce.

const data = [{
  id: 1,
  count: 3,
  alt_count: 2
}];

const countObj = data.reduce((acc, curr) => {
  return {
    count: acc.count + curr.count,
    alt_count: acc.alt_count + curr.alt_count,
  };
}, {
  count: 0,
  alt_count: 0
});

console.log(countObj);

edited Apr 10, 2023 at 5:17

Chandrashekhar Kase

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answered Apr 7, 2022 at 12:03

Clarity

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