How to Create a New Array with a Custom Structure from an Existing Array in JavaScript

Learn how to transform an array in JavaScript by filtering and restructuring data based on specific conditions.
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How to Create a New Array with a Custom Structure from an Existing Array in JavaScript

If you're working with JavaScript, you might encounter scenarios where you need to transform an existing array into a new one based on certain conditions. In this post, we are going to explore how to create a new array from an origin array using specific conditions and a different data structure. Let's dive into a practical example to make things clearer.

The Problem Statement

Imagine you have an array of user objects, each containing information about the users, including their names and license numbers. The goal is to filter out the users who either have an empty or null license number and return a new array where each element is structured as follows:

The licenseNumber is the key

The name is the value

Here's the original data set we are going to work with:

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

Steps to Achieve the Solution

Step 1: Filter the Users

First, we need to filter out the users whose licenseNumber is either empty or null. In JavaScript, the filter() method can help us with this task. It goes through each element in the array and returns a new array containing only those elements that meet the specified condition.

Step 2: Map to the New Structure

After filtering, we can then use the map() method to create a new array with the desired structure. The map() method constructs a new array populated with the results of calling a provided function on every element in the calling array.

Implementation

Here’s how to implement the above logic in code:

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

Output

The output of the above code will be an array of objects where each object contains the license number as the key and the corresponding user name as the value:

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

Alternative Approach: Using forEach Loop

If you prefer to iterate over the array only once, you can use a forEach loop instead of chaining filter and map. This approach manually builds your result array by checking each user's license number and pushing them to the result if valid:

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

This method might be more efficient in certain situations since it avoids creating intermediate arrays.

Conclusion

Transforming an array based on specific conditions and restructuring it in JavaScript can be easily accomplished using filter() and map(). Alternatively, using a loop such as forEach provides a more streamlined approach for certain use cases. Whether you choose to go with one method or the other ultimately depends on your specific requirements and preferences.

Feel free to try out these methods in your own projects, and modify them based on your needs! Happy coding!