How to return unmatched item from two objects in Javascript

Question

I have the following objects

defaultObject = {
  item1: ""
  item2: 2
  item3: 3
  item4: ""
}

newObject = {
  item1: 1
  item2: 4
  item3: 3
  item4: "something"
}

Output which I expect is as below

{
  item1: 1
  item2: 4
  item4: "something"
}

I tried Compare two Arrays with Objects and create new array with unmatched objects.

What did you try exactly? You have objects, not arrays so you would have to loop over Object.entries — epascarello, May 04 '21 at 19:38
Is preserving the keys a requirement? What if the two objects have different values for the same key> — Sergiu Paraschiv, May 04 '21 at 19:39
Yes, If the two objects have different values for the same key > then it will return from `newObject`. — Sofia Ansari, May 04 '21 at 19:46

score 0 · Accepted Answer · answered May 04 '21 at 20:13

This should do it:

oldo = {
  item1: "",item2: 2,
  item3: 3,item4: ""
}

newo = {
  item1: 1,item2: 4,
  item3: 3,item4: "something"
}
const res=Object.entries(newo).reduce((a,[k,v])=>(oldo[k]==v||(a[k]=v),a),{});
console.log(res);

The res object is made up of only those entries (properties) that are not found in the oldo object.

How to return unmatched item from two objects in Javascript

1 Answers1