Javascript - how to merge two objects preserving the values of the first one?

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I have two objects with the same keys and I need to merge them preserving the values of the first object. For instance:

JavaScript

var obj1 = {
	1: "John",
	2: "Tom",
	3: "Harry"
};

var obj2 = {
	1: "Doe",
	2: "Jones",
	3: "Newman" 
};

Desired output:

JavaScript

var obj3 = {
	1: "John Doe",
	2: "Tom Jones",
	3: "Harry Newman"
};

This is what I've tried:

JavaScript

var obj3 = {};

for (var item in obj1) {
	obj3[item] = obj1[item] + " " + obj2[item];
};

It works. But is there a better/simpler way to achieve what I need?

What I have tried:

JavaScript

var obj3 = {};

for (var item in obj1) {
	obj3[item] = obj1[item] + " " + obj2[item];
};

Posted 6-Oct-23 12:16pm

LB2371

Updated 6-Oct-23 12:18pm

v2

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Andre Oosthuizen · Accepted Answer · 2023-10-07T03:15:00

There is nothing wrong with your code and it is down to the point, however, if you're looking for a more concise and modern way you can use the 'Object.keys' method along with 'Array.prototype.reduce' to create your merged object.
The Object.keys() static method [^]
The reduce() method [^]

JavaScript

const obj1 = {
  1: "John",
  2: "Tom",
  3: "Harry"
};

const obj2 = {
  1: "Doe",
  2: "Jones",
  3: "Newman"
};

const obj3 = Object.keys(obj1).reduce((result, key) => {
  result[key] = `${obj1[key]} ${obj2[key]}`;
  return result;
}, {});

console.log(obj3);

I have created a fiddle for you which gives the desired output -
Merged object [^]