Given two equal objects, filter only the differences

Lets say I have two different objects

let obj1 = {
  "value1" : "1",
  "value2" : "2",
  "value3" : "3",
  "value4" : "4"
}

let obj2 = {
  "value1" : "1",
  "value2" : "3",
  "value3" : "3",
  "value4" : "5"
}

I need a the differences in a new object that will depend on obj2

result = { "value2":"3" , "value4" : "5" }

The case can be too , that obj1 === undefined
In that case, I need all the values from obj2

Currently I have

let result = {}
let singleChange = false

for (const i of Object.entries(obj2)) {
    if (obj1 && obj1[i[0]] !== i[1]) {
      result [i[0]] = i[1];
      singleChange = true
    } else if(!singleChange) {
      result = obj2;
    }
  }

But it doesnt really sem to work properly all the times. Is there a better way to write this?

>Solution :

A modern version with entries and fromEntries:

let obj1 = {
  "value1" : "1",
  "value2" : "2",
  "value3" : "3",
  "value4" : "4"
}

let obj2 = {
  "value1" : "1",
  "value2" : "3",
  "value3" : "3",
  "value4" : "5"
}

let obj3 = undefined;

function objIntersection(o1, o2) {
  const filteredArray = Object.entries(o2)
  .filter(([k,v]) => o1?.[k] !== v);

  return Object.fromEntries(filteredArray);
}

console.log(objIntersection(obj1, obj2));
console.log(objIntersection(obj3, obj2));