How to Fetch and Group JSON Results by Key in JavaScript

This guide provides a detailed solution for grouping JSON results by a specific key using JavaScript's `fetch` API. Learn how to count occurrences of categories and get accurate results.
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How to Fetch and Group JSON Results by Key in JavaScript

When working with APIs in JavaScript, it's common to receive data in JSON format. One tricky problem developers often face is how to efficiently group these results based on a specific key. If you've ever used the fetch API to retrieve data and needed to count occurrences of categories, you're in the right place! In this article, we'll dive into a practical example that illustrates how to correctly group results from a JSON response.

Understanding the Problem

Imagine you have an array of objects returned from an API call, like this:

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

The goal is to group these results by the Var2 key and count how many occurrences there are for each category (e.g., abc, cda, fff, ddd).

For this, you might have something like this in a separate list of categories:

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

The Solution

To achieve the desired result, you'll want to make sure your code checks if each Var2 contains one of the values from listOfVariables. Here's a step-by-step breakdown of the code to accomplish this.

Step 1: Fetch Data

First, we use the fetch method to get the data from the specified API.

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

Step 3: Loop Through Data

Now, iterate through each element of the resulting data and check if the Var2 value belongs to the listOfVariables.

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

Step 4: Prepare Final Results

Finally, create your finalResult, iterating over listOfVariables to set counts or default to 0 if no occurrences were found.

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

Example of Final Output

Now, if the data is processed correctly, your output for the counts will resemble:

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

Conclusion

With a better understanding of how to use fetch and group results by key in JavaScript, accessing and processing API data becomes a breeze.

To summarize this solution:

We fetched data using the fetch API.

We counted occurrences of each category key dynamically using an array of possible categories.

We returned results in a structured format that’s easy to read.

Feel free to use this pattern in your own JavaScript projects whenever you need to group and count similar data from API responses. Happy coding!