arr.reduce((total, obj) => obj.credit + total,0)

// 3

​

const arr = [ { 'name': 'P1', 'value': 150 }, { 'name': 'P1', 'value': 150 }, { 'name': 'P2', 'value': 200 }, { 'name': 'P3', 'value': 450 } ];

​

const sumByKey = (arr, key, value) => {

  const map = new Map();

  for(const obj of arr) {

    const currSum = map.get(obj[key]) || 0;

    map.set(obj[key], currSum + obj[value]);

  }

  const res = Array.from(map, ([k, v]) => ({[key]: k, [value]: v}));

  return res;

}

​

console.log(sumByKey(arr, 'name', 'value')); // 'name' = value to group by, 'value' = value to sum

 Run code snippet

const fruits = [

  {

    type: "oranges",

    amount: 10,

  },

  {

    type: "apples",

    amount: 0,

  },

  {

    type: "oranges",

    amount: 5,

  },

];

​

const endresult = Array.from(

  fruits

    .reduce((map, curr) => {

      if (!map.has(curr.type)) map.set(curr.type, { ...curr, count: 1 });

      else {

        map.get(curr.type).amount += curr.amount;

        map.get(curr.type).count++;

      }

      return map;

    }, new Map())

    .values()

);

​

console.log(endresult);