Add Key and Value to an Array of Objects Using JavaScript

Learn how to dynamically add key-value pairs from an array to an array of objects in JavaScript. This guide walks you through the process step by step, making it easy to reuse!
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Add Key and Value to an Array of Objects Using JavaScript

In the world of programming, particularly in JavaScript, manipulating data structures like arrays and objects is a common task. You might find yourself needing to enhance an array of objects by adding key-value pairs based on an existing array of keys. This can seem complex at first, especially when looking to make a reusable utility function. Here, we’ll break down how you can achieve this in a clear and structured way.

The Problem

You have the following data structure representing an array of objects:

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Additionally, you have an array that contains the keys you want to add:

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And an object template that you want to update per entry in your array of objects:

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Your goal is to expand this obj into a new array of objects, each enriched with key-value pairs from arr. For example, you want the resulting object for 'one' to look like this:

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

This process needs to be dynamic enough to handle different arrays and keys.

The Solution

To solve this problem, we’ll write a reusable function that utilizes the map() method along with forEach() to iterate over our object template and the keys. Here's how to do it step-by-step:

Step 1: Visualizing the Data

We will use the following setup:

json: Our initial array of objects containing various properties.

objs: The array of objects based on the property cat.

arr: The array of keys we want to extract.

Step 2: Implementation

Here’s the implementation of our solution:

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

Explanation of the Code

Mapping Through Objects: We utilize the map() function on the objs array, which will iterate through each object.

For Each Key: Inside the mapping function, we use forEach() on the arr to add each specified key-value pair from json into the current object.

Dynamic Assignment: We dynamically assign the value from json[i][key] to the object based on the current index i.

Resulting Array: Finally, we log the resulting array to see our enriched objects.

Working of the Final Output

With this code, you'll get an output that contains a new structure of objects, each having the key-value pairs you’ve specified:

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

Conclusion

By following this guide, you've learned how to easily and dynamically add key-value pairs from an array to an array of objects in JavaScript. This approach not only simplifies your code but also makes it reusable for different datasets and structures. As you continue to work with JavaScript, you'll find this pattern useful for various data manipulation tasks.

Now you can confidently implement this functionality in your projects, enhancing your data-handling skills in JavaScript!