如何求和对象数组中相同字段的值？

function sumObjectsByField(objects, field) {
  var result = {};
  
  for (var i = 0; i < objects.length; i++) {
    var obj = objects[i];
    var value = obj[field];
    
    if (result.hasOwnProperty(value)) {
      result[value] += value;
    } else {
      result[value] = value;
    }
  }
  
  return result;
}

var objects = [
  { name: 'A', value: 10 },
  { name: 'B', value: 20 },
  { name: 'A', value: 30 },
  { name: 'C', value: 40 }
];

var result = sumObjectsByField(objects, 'name');
console.log(result);

{
  A: 40,
  B: 20,
  C: 40
}