JSFiddle - React, Tailwind, and code Playground

JavaScript

data = [{
  id: 'name1',
  num1: 12,
  num2: 8
}, {
  id: 'name2',
  num1: 5,
  num2: 13
}, {
  id: 'name3',
  num1: 21,
  num2: 4
}];

var Sum = {};
data.forEach(function(obj) {

  var keys = Object.keys(obj);
  keys.forEach(function(k) {
  if( i )
    if (Sum.hasOwnProperty(k)) {
      Sum[k] += obj[k];
    } else {
      Sum[k] = obj[k];
    }
  })
})

console.log(Sum);