Sum all objects by their key name

Question

I'd like to Sum all objects by their key name using loop. The key "id" will be delete

var arr = [{id:1, "my color":1,"my fruit":4},{id:2,"my color":2,"my fruit":4},etc];

var merged = arr.reduce(function(previousValue, currentValue) {
     return {
            "my fruit": previousValue["my fruit"] + currentValue["my fruit"],
            "my color": previousValue["my color"] + currentValue["my color"],
             etc:...
          }
        });

I'd like this result

result = [{"my color":3},{"my fruit":8},etc];

So, what goes wrong with the provided code? What is the question? — Teemu, Jun 12 '18 at 10:42
You can call the function from the post I linked with `sumObjectsByKey(...arr)` — baao, Jun 12 '18 at 10:47
I don't know it doesn't works for another array. I think the problem is when for some keys if the value is NaN — observatoire, Jun 12 '18 at 10:48

score 0 · Accepted Answer · answered Jun 12 '18 at 10:46

0

Rather than hard-coding the keys, it would be more flexible if you iterated over all keys in the object inside the reduce function and add them to the result, that way the input objects can have arbitrary key/number pairs:

const arr = [{id:1, "my color":1,"my fruit":4},{id:2,"my color":2,"my fruit":4}];
const res = arr.reduce((a, { id, ...rest }) => {
  Object.entries(rest).forEach(([key, val]) => {
    a[key] = (a[key] || 0) + val;
  });
  return a;
}, {});
console.log(res);

answered Jun 12 '18 at 10:46

CertainPerformance

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And how could I get their percent (value/sum of values) and not their sum ? like this { "my color": 27, "my fruit": 73 } – observatoire Jun 12 '18 at 14:23
Sum up the `values` of the result, then divide each value by the sum – CertainPerformance Jun 12 '18 at 21:48

Sum all objects by their key name

1 Answers1