JavaScript/TypeScript - Object assign only available properties

Question

Following usecase: Lets assume I have an object with following properties:

const objOne = {
  car: 'ford',
  location: 'Munich',
  driver: 'John'
}

and a second Obj that only has some of the first Obj's properties:

const objTwo = {
  car: 'BMW',
  driver: 'Marta'
}

Is there a way to assign the properties from the second obj to the first obj without loosing the properties from the first obj. In this case location: 'Munich'. I know for a fact there is a method like Object.assign but this method completely copies the targeted obj, which I obviously don't want to.

What is the desired output?

Hassan Imam
– Hassan Imam

2018-08-02 07:39:34 +00:00
Commented Aug 2, 2018 at 7:39 — Hassan Imam
– Hassan Imam, Commented Aug 2, 2018 at 7:39
In matter of fact this is what Object.assign will do

Hyyan Abo Fakher
– Hyyan Abo Fakher

2018-08-02 07:40:26 +00:00
Commented Aug 2, 2018 at 7:40 — Hyyan Abo Fakher
– Hyyan Abo Fakher, Commented Aug 2, 2018 at 7:40

knee pain · Accepted Answer · 2018-08-02 07:50:09Z

7

This is exactly the behaviour of Object.assign

The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.

const objOne = {
  car: 'ford',
  location: 'Munich',
  driver: 'John'
}
        
const  objTwo = {
  car: 'BMW',
  driver: 'Marta'
}

console.log(objOne);
console.log(objTwo);

Object.assign(objOne, objTwo);
console.log('--assign--');
console.log(objOne);

edited Aug 2, 2018 at 7:50

answered Aug 2, 2018 at 7:44

knee pain

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1 Comment

MarcoLe Over a year ago

Oh I messed up, thanks for the clearification. I really thought that the first objs. gets completely overwritten by the second one....

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