How to Combine Arrays of Objects Using ES6 Functions

Learn how to effectively `combine arrays` of objects by `id` using ES6’s powerful functions. This guide covers the steps and code to help you manage objects and arrays easily.
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How to Combine Arrays of Objects Using ES6 Functions

In the world of JavaScript, handling arrays of objects is a common task. One scenario you might encounter is needing to combine multiple objects with a common identifier (like catId) into a single cohesive structure. This helps make data more organized and easily manageable. In this post, we'll explore how to accomplish this using ES6 functions, specifically focusing on the reduce() method.

The Problem Statement

Imagine you have the following array of objects, where each object contains an id and a catId:

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

Your goal is to transform this array into a new format where each unique catId is represented as a separate object, containing an array of associated ids:

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

The Solution with ES6 Functions

To achieve this transformation, we'll leverage the reduce() method from ES6. This method allows us to accumulate values into a single result, making it perfect for grouping objects.

Step-by-Step Breakdown of the Solution

Initialize the Reduce Function: We'll start with an accumulator object that will hold our grouped data. Each key in this object will be a catId, and the value will be an object containing that catId and its associated topicIds.

Destructure Each Object: In each iteration, we'll destructure the current object to get the id and catId.

Group the Data: We'll check if the catId already exists in the accumulator. If it doesn't, we'll initialize it with a new object containing an empty topicIds array.

Push the id into the Array: Regardless of whether the catId was already in the accumulator or not, we'll push the current object's id into the corresponding topicIds array.

Example Code

Here’s how the complete solution looks in code:

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

Explanation of the Code

reduce Method: We call reduce() on the array a, providing it an initial empty object {} as the accumulator.

Accumulator Logic: Inside the callback, we check if acc[catId] exists. If not, we create a new object for that catId.

Pushing IDs: We then push the id into the array of topicIds which corresponds to the category.

Final Output

When we run the code, we get an output that matches our expected format:

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

Conclusion

Combining array objects by a common identifier using ES6 functions is a straightforward process when you utilize the reduce() method. With just a few lines of code, you can transform data into a more structured and manageable format. This approach is beneficial for maintaining organized data in applications, especially as complexity grows. Happy coding!