How to Group Objects in an Array by ID in JavaScript

Learn how to properly add new objects to an array and group them by ID using JavaScript without using reduce.
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Grouping Objects in an Array by ID in JavaScript

Have you ever faced the challenge of needing to add new objects to an array while maintaining a specific structure? In JavaScript, this task can often become convoluted, especially without the use of modern methods. In this post, we will address a common scenario where you want to group objects by their id field in an array, transforming your initial array into a more structured format. We will go through a sample code and show you how to achieve the desired output step by step.

The Problem

Imagine you have an array of objects, where each object has fields like id, name, and email. Your goal is to group these objects by their id, so that each id points to an array of the corresponding objects. The initial example provides objects with non-unique IDs, and you want to structure them into a new object format.

Example Input

Here's the initial data array:

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

Desired Output

Your desired output format looks like this:

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

The Solution

Step-by-Step Breakdown

To achieve the desired structure without using array methods such as reduce, you can follow these steps:

Initialize the Data: Start with the given structure of result, which contains the field array.

Create a New Object for Grouping: Initialize an empty object groups that will store your grouped data.

Iterate Through the Results: Use a for loop to iterate through results, and for each object, check if the id has been seen before.

Group the Data: If the id is not in groups, create a new key in the object for that id and initialize it with an empty array.

Push the New Objects: For every iteration, push a new object containing the name and email to the corresponding id array in the groups.

Final Code

Here is the final code that implements the above logic:

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

Output of the Code

When you run the above code, you will get the expected output:

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

Conclusion

In this guide, we walked through how to group objects in an array by their id in JavaScript. By breaking down the problem into clear steps, we formulated a solution that can effectively categorize and organize your data without relying on modern array methods. This not only enhances the understanding of data structures in JavaScript but also prepares you to handle various data manipulation scenarios in programming. Happy coding!