How can I compare two objects and reassign the second object only with the properties that are different from the first object?

Question

Here my first object

const initialValues = {
  prenom: "anne",
  nom: "dupont",
  age: 24
}

Here my second object

const newValues = {
  prenom: "anne",
  nom: "duclos",
  age: 25
}

What I want is when these two objects will be compared, newValues will contain only property that are different from initialValues. It'll return :

newValues = {
  nom: "duclos",
  age: 25
}

Here what I've been able to do so far:

const initialValues = {
  prenom: "anne",
  nom: "dupont",
  age: 24
}
const newValues = {
  prenom: "anne",
  nom: "duclos",
  age: 25
}

function keepChangedValues(object1, object2) {
    
  const keys1 = Object.keys(object1);
  const keys2 = Object.keys(object2);


  for (let key of keys1) {
    if (object1[key] === object2[key]) {
       
        //delete this propreties from newValues
    }
  }
}
keppChangedValues(initialValues, newValues)

Thank you for you help !

Do you mean you want to create a 3rd object that has the properties that are different between the first 2? — tmdesigned, Nov 25 '20 at 13:11
Not exactly. I want to keep newValues object but change his propreties. Without creating a 3rd object. I don't know if it's possible. — user13512145, Nov 25 '20 at 13:26
Does this answer your question? [JavaScript equivalent of jQuery's extend method](https://stackoverflow.com/questions/11197247/javascript-equivalent-of-jquerys-extend-method) — Jonathan Pasquier, Nov 25 '20 at 13:35
So you want to `delete` all properties from `newValues` that already exist with the same value in `initialValues`? — Bergi, Nov 25 '20 at 13:42
@user13512145 then do just that in your loop (but name the function something else than `shallowEqual`) — Bergi, Nov 25 '20 at 14:04

Henock · Answer 1 · 2020-11-25T13:50:46.557

1

If you nkow object properties you can add this:

var newObject = {};
if(newValues.prenom != initialValues.prenom) newValues.prenom = newValues.prenom;
if(newValues.nom != initialValues.nom) newObject.nom = newValues.nom;
if(newValues.age != initialValues.age) newObject.age = newValues.age;

edited Nov 25 '20 at 13:50

answered Nov 25 '20 at 13:45

Henock

98
11

score 0 · Answer 2 · answered Nov 25 '20 at 22:52

0

I find the solution. I just need to add inside the if statement delete object2[key]

In this way, ONLY the propreties of the 2nd object which have the same value as the first object will be deleted from the 2nd object.

answered Nov 25 '20 at 22:52

user13512145

45
1
5

How can I compare two objects and reassign the second object only with the properties that are different from the first object?

2 Answers2