javascript - How to merge each object within arrays by index?

Question

How can I merge two arrays of objects of same length?

var array1 = [
  {name: "lang", value: "English"}, 
  {name: "age", value: "18"}
];
var array2 = [
  {code: "EN", text: "English language"}, 
  {code: "DE", value: "German", text: "German language"}
];

The goal is to create the following array:

var array3 = [
  {name: "lang", value: "English", code: "EN", text: "English language"}, 
  {name: "age", code: "DE", value: "German", text: "German language"}
];

The idea is to create a new array in which array1 is the base and array2 overrides the values if they share the same key, and otherwise adds to the base array. The merging should happen sequentially in the same order that the objects appear in each array.

In this example, the arrays contains two objects, but for my actual situation, I have a couple of dozens of objects.

This is what I’ve been trying to do, but this only merges the first set of objects:

var array3 = Object.assign(array1[0], array2[0]);

How can I loop through it or map it?

Answer 1

A simple map with object spread syntax will do it. Instead of object spread, Object.assign can also be used. Assign unto a new empty object in order to avoid mutating the existing objects.

var array1 = [
    { name: "lang", value: "English" }, 
    { name: "age", value: "18" }
  ];
var array2 = [
    { code: "EN", text: "English language" }, 
    { code: "DE", value: "German", text: "German language" }
  ];

var array3 = array1.map((obj, index) => ({
    ...obj,
    ...array2[index]
  }));
var array3Alternative = array1.map((obj, index) => Object.assign({}, obj, array2[index]));

console.log(array3);