How to Merge Objects in an Array by Adding Elements from Another Array

A comprehensive guide on how to merge objects from two arrays in JavaScript by adding elements of one array to another. Ideal for beginners and intermediate developers.
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How to Merge Objects in an Array by Adding Elements from Another Array

When working with arrays of objects in JavaScript, there may come a time when you need to merge data from two separate arrays. This could happen, for instance, when you are making HTTP requests and receiving multiple sets of related data. The challenge arises when you want to combine these arrays in a meaningful way, particularly when they hold related information about the same entities.

The Problem

Imagine you have two arrays of objects. The first array contains names and ages of individuals, while the second array contains their corresponding genders. Here’s how these arrays might look:

[[See Video to Reveal this Text or Code Snippet]]

You might want to merge these arrays so that each object in the first array now also contains the gender information from the second array, resulting in a structure like:

[[See Video to Reveal this Text or Code Snippet]]

However, if you attempt to join these two arrays using the spread operator, like this:

[[See Video to Reveal this Text or Code Snippet]]

You will end up with an unintended result:

[[See Video to Reveal this Text or Code Snippet]]

This is clearly not what you want. So, how can you achieve the desired structure?

The Solution

To merge the two arrays correctly, you’ll want to combine objects at the same index from both arrays. Here's how you can do that using the map function along with the object spread operator:

Step-by-Step Guide

Use the map Method: The map method will allow you to iterate over the first array (data1), applying a function to each element.

Access Elements by Index: Within the map function, you can use the second parameter as the index to access the corresponding element in the second array (data2).

Merge Using Spread Operator: Use the spread operator to combine the properties of each object into a single object.

Here’s the code that accomplishes this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

...x and ...data2[i]: The spread operator takes all properties from the current object x and merges them with the properties of the object at the same index i from data2.

Final Output

When you run the code, the result will look like this:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Merging objects from two arrays in JavaScript can be simply achieved by leveraging the map method and the object spread operator. By accessing corresponding elements by their index and merging them, you can create a more informative structure that consolidates data from both sources. This technique is particularly useful in real-world applications where data is often fragmented across different API responses.

Feel free to try this out in your coding projects, and you’ll see how powerful and efficient JavaScript can be in handling such tasks!