How to filter an array of objects and get distinct values based on a specific property

Learn how to effectively filter an array of objects and retrieve distinct values based on a specific property using JavaScript in a concise and efficient manner.
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How to Filter an Array of Objects and Get Distinct Values Based on a Specific Property

When working with arrays in JavaScript, especially those containing objects, you might encounter a requirement to filter data based on specific criteria while also ensuring that the resulting dataset contains only unique entries. In this post, we'll tackle a common scenario: filtering an array of objects to get distinct values based on a specified property.

The Problem

Consider the scenario where you have an array of objects representing different classes, groups, and their corresponding values:

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

From this dataset, you need to filter out the objects where the Class is "Class C" and then get distinct entries based on the Group property. While the initial solution might seem adequate, there’s a more efficient and cleaner way to achieve this.

The Solution

To solve this problem effectively, we can use a combination of filtering and reducing operations. Here's a step-by-step breakdown of how to implement this:

Step 1: Filtering by Property

First, we need to create a function that allows us to filter items based on a specific property value:

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

Step 2: Distinct Values by Property

Next, we will define another function to extract distinct items based on a specified property:

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

Step 3: Implementing the Functions

Now that we have our functions, let's use them to filter for "Class C" and get distinct groups. Here’s how you can implement it:

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

Expected Output

Running this code will give you the following distinct items where Class is "Class C":

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

Customization for Last Entries

If your requirement changes to retrieve the last item found per distinct group instead of the first, you can easily modify the distinctByProp function by removing the check for existing properties. This modification will ensure that the last encountered item for each group gets preserved.

Conclusion

This approach effectively separates the concerns of filtering and grouping objects in an array. By utilizing higher-order functions in JavaScript, we streamline our code, making it more readable and easier to maintain. Testing and adjusting these functions to meet different needs can also be done with minimal effort.

With this guide, you should feel equipped to tackle similar challenges when working with arrays of objects in JavaScript. Happy coding!