Sum multiple keys and merge to one object based off a specific key

You can reduce the array to an accumulator object (a) by destructuring each object into its name and values, and summing all the values for each name in the accumulator object. Then you just need to retrieve the accumulator's object values to get to your final result:

const result = Object.values(data.reduce((a, {name, ...values}) => {
  a[name] ??= { name };
  Object.entries(values).forEach(([key, value]) => {
    a[name][key] ??= 0;
    a[name][key] += value;
  });
  return a;
} , {}));

This solution has a time complexity of O(n). It will gracefully handle cases where new values are added (value4, value5, ...), and cases where not all values are present in all objects.

Complete snippet:

const data = [{
  name: "test1",
  value1: 100,
  value2: 100,
  value3: 100
}, {
  name: "test1",
  value1: 100,
  value2: 100,
  value3: 100
}, {
  name: "test2",
  value1: 200,
  value2: 100,
  value3: 100
}, {
  name: "test2",
  value1: 200,
  value2: 100,
  value3: 100
}, {
  name: "test3",
  value1: 100,
  value2: 100,
  value3: 100
}];

const result = Object.values(data.reduce((a, {name, ...values}) => {
  a[name] ??= { name };
  Object.entries(values).forEach(([key, value]) => {
    a[name][key] ??= 0;
    a[name][key] += value;
  });
  return a;
} , {}));

console.log(result);

It can be achieved using Map and reduce.

while using Map here is a code:

const map = new Map();

for (const item of data) {
  if (!map.has(item.name)) {
    map.set(item.name, {
      name: item.name,
      value1: item.value1,
      value2: item.value2,
      value3: item.value3
    });
  } else {
    map.get(item.name).value1 += item.value1;
    map.get(item.name).value2 += item.value2;
    map.get(item.name).value3 += item.value3;
  }
}
console.log(Array.from(map.values()));

and while using reduce it can be done like this

const groupedSum = data.reduce((acc, curr) => {
  const objIndex = acc.findIndex(obj => obj.name === curr.name);
  if (objIndex === -1) {
    acc.push({ name: curr.name, value1: curr.value1, value2: curr.value2, value3: curr.value3 });
  } else {
    acc[objIndex].value1 += curr.value1;
    acc[objIndex].value2 += curr.value2;
    acc[objIndex].value3 += curr.value3;
  }
  return acc;
}, []);
console.log(groupedSum);

For example:

const total_sum_data = (arr, key) => {
  const map = new Map();
  for (const obj of arr) {
    const groupKey = obj[key];
    if (!map.has(groupKey)) {
      map.set(groupKey, { [key]: groupKey });
    }
    const currObj = map.get(groupKey);
    Object.keys(obj).forEach(k => {
      if (k !== key) {
        currObj[k] = (currObj[k] || 0) + obj[k];
      }
    });
  }
  return Array.from(map.values());
};

console.log(total_sum_data(arr,"name")); 

Hope below logic will help you

let array = [
  { 
    name: "test1",
    value1: 100,
    value2: 100,
    value3: 100
  },
  { 
    name: "test1",
    value1: 100,
    value2: 100,
    value3: 100
  },
  { 
    name: "test2",
    value1: 200,
    value2: 100,
    value3: 100
  },
  { 
    name: "test2",
    value1: 200,
    value2: 100,
    value3: 100
  }, 
  { 
    name: "test3",
    value1: 100,
    value2: 100,
    value3: 100
  },

]


let reduceArr = array.reduce((prev, next) =>{
    if (next.name in prev) {
      prev[next.name].value1 += next.value1;
      prev[next.name].value2 += next.value2;
      prev[next.name].value3 += next.value3;
    } else {
       prev[next.name] = next;
    }
    return prev;
  }, {});

let result = Object.values(reduceArr);


console.log(result)