How to Group Objects in a Nested Array Using JavaScript

Learn how to effectively `group`, `reduce`, and convert arrays of objects into nested structures based on multiple columns using JavaScript.
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Grouping Objects in a Nested Array Using JavaScript

When working with data in JavaScript, you may often find yourself needing to organize and group your records. This is especially common when you have an array of objects and want to structure them based on specific attributes. In this guide, we'll walk through the challenge of grouping an array of objects by two columns and provide a solution to achieve that.

The Problem: Grouping Based on Two Columns

Imagine you have an array of objects that looks like this:

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

In the above array, you want to group items by col2 and nest objects under col1 and col3. The goal is to achieve an output structure similar to this:

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

The Solution: How to Group the Objects

To achieve this structured output, you need to utilize the reduce method in JavaScript effectively. Here’s how you can do it, step by step.

Step 1: Initialize the Reduce Function

Start by declaring the function that will work through the array and group the objects by col2:

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

Step 2: Find Existing Groups

Within the function, check if a group already exists for the current col2 value:

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

Step 3: Assign and Push Values

If the group exists, push new values into col1 and col3. If it doesn't, create a new group and push it to the result:

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

Complete Code Example

Here's the complete script that produces the desired result:

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

Conclusion

Grouping an array of objects by multiple columns is a powerful technique in data manipulation using JavaScript. By utilizing the reduce method and careful checking of groups, you can transform your data into a much more organized, nested structure. Now you have the tools to easily group and structure your JavaScript objects efficiently!