JavaScript - Return differences between two Objects?

var data = {
  "48": "{\"sid\":\"48\",\"name\":\"title 1\"}",
  "77": "{\"sid\":\"77\",\"name\":\"The blahblah title\"}",
  "83": "{\"sid\":\"83\",\"name\":\"The blahblah derp\"}",
  "87": "{\"sid\":\"87\",\"name\":\"The derpy title 4\"}"
};

var obj1 = {
  "48": "{\"sid\":\"48\",\"name\":\"title 1\"}",
  "77": "{\"sid\":\"77\",\"name\":\"The blahblah title\"}"
};

var result = {};
var keys = Object.keys(obj1);

for (var key in data) {
 if (!keys.includes(key)) {
  result[key] = data[key];
 }
}

console.log(result);

const obj1 = {
  '48': '{"sid":"48","name":"title 1"}',
  '77': '{"sid":"77","name":"The blahblah title"}',
}

const obj2 = {
  '48': '{"sid":"48","name":"title 1"}',
  '77': '{"sid":"77","name":"The blahblah title"}',
  '83': '{"sid":"83","name":"The blahblah derp"}',
  '87': '{"sid":"87","name":"The derpy title 4"}',
}

const combinedObject = { ...obj1, ...obj2 }

const diff = Object.entries(combinedObject).reduce((acc, [key, value]) => {
  if (
    !Object.values(obj1).includes(value) ||
    !Object.values(obj2).includes(value)
  )
    acc[key] = value

  return acc
}, {})

console.log(diff)