How to Add a Key-Value Pair to an Array of Objects in JavaScript

Learn how to efficiently add a `completed` key with a value of `false` to every object in an array of objects in JavaScript. This guide provides a step-by-step approach you can easily follow.
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Adding Key-Value Pairs in Nested Arrays in JavaScript

When working with arrays and objects in JavaScript, you may find yourself needing to modify structures by adding new key-value pairs. This can be particularly useful in applications that involve managing user data or processing responses that come from APIs. In this post, we will address a common scenario: how to add a key-value pair to every object in an array—and even within nested objects.

The Problem

Suppose you have a JavaScript response from an API call that looks like this:

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

Your goal is to add a "completed" key with a value of false to both objects at two different levels: the main object level and inside the company object. After modification, the expected output should be:

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

The Solution

We can solve this problem efficiently using the .map() method in JavaScript, which allows us to create a new array and modify its contents based on the existing data. Here’s how you can do it step by step:

Step 1: Create the Initial Input Array

Define your input array which resembles the structure provided from the API:

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

We’ll use .map() to iterate over each object in the array and add the "completed" key:

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

Final Code Snippet

Here is the complete code that implements the above steps:

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

Conclusion

Using JavaScript's .map() function, you can easily modify arrays of objects to include additional properties, enabling better data management in your applications. This approach not only keeps your code clean but also ensures a functional programming style by returning new modified arrays without mutating the original input.

By following these steps, you can efficiently manage and manipulate complex data structures as your JavaScript projects grow. Happy coding!