10 examples of 'javascript sum array of objects by key' in JavaScript

5
function sumByKey(items, key) {
6
  const sum = items.reduce((prevSum, item) => prevSum + item[key], 0);
7
  return sum;
8
}

1283
function arrayToObjectsById(array, keyOf) {
1284
    return array.reduce(function (objectsById, item) {
1285
        objectsById[keyOf(item)] = item;
1286
        return objectsById;
1287
    }, {});
1288
}

24
function sumCountObjects(obj1, obj2) {
25
  return Object.keys(obj2).reduce((summaryObj, key) => {
26
    if (summaryObj[key] == null) {
27
      summaryObj[key] = obj2[key];
28
    } else {
29
      summaryObj[key] += obj2[key];
30
    }
31
    return summaryObj;
32
  }, Object.assign({}, obj1));
33
}

66
function sum(array){
67
	var s = 0;
68
	for(var i = 0; i < array.length; i++){
69
		s += array[i];
70
	}
71
	return s;
72
}

45
function iterativeSum(array) {
46
  let total = 0;
47
  array.forEach(function (n) {
48
    total += n;
49
  });
50
  return total;
51
}

2
function sum(...nums) {
3
  if (nums.length === 1 && Array.isArray(nums[0])) {
4
    nums = [...nums[0]];
5
  }
6
  return nums.reduce((a, b) => a + b);
7
}

116
function mySumFunction(array, sum) {
117
    console.log(array.reduce(sum));
118
    console.log('-----------------------');
119
}

37
function arraySum(array) {
38
  return array.reduce(
39
    (sum, curr) =>
40
      sum + (curr ? 1 : 0) // if curr is 0 (no edge) or undefined (loop not allowed), sum remains unchanged
41
    , 0,
42
  );
43
}

25
function Sum(array) {
26
    // Computes array[0] + array[1] + ... + array[n-1]
27
    var tsum = 0;
28
    for(var i = 0, l = array.length;i

494
export function arraySum (array: NumberArray, stride = 1, offset = 0) {
495
  const n = array.length
496
  let sum = 0
497
  for (let i = offset; i < n; i += stride) {
498
    sum += array[ i ]
499
  }
500
  return sum
501
}