Using TypeScript's reduce to Split Arrays of Objects by Property

Learn how to effectively use TypeScript's reduce method to transform an array of objects into separate arrays based on a specific property, making data access easier and more efficient.
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Splitting Arrays of Objects by Property in TypeScript

When working with arrays of objects in TypeScript, you might encounter a situation where you need to group these objects based on a specific property. For example, suppose you have an array of delivery statistics that includes various materials identified by materialId. It can be challenging to manage this data if you want to easily access all entries associated with specific materialId values. In this guide, we'll explore how to tackle this problem by leveraging TypeScript's reduce method.

The Challenge

Imagine you have the following array of delivery statistics:

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

Your goal is to reorganize this data into an object where each materialId serves as a key, and its value is an array of all objects that share that materialId. For example, your desired output looks like this:

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

This format allows you to easily access information by the material type, improving the efficiency of data handling.

The Solution: Using reduce

The reduce method is a powerful tool for transforming arrays in JavaScript and TypeScript. Here’s how you can utilize it in this context:

Step-by-Step Implementation

Define the Initial Array: Start with your array of statistics.

Use reduce to Create the Output Structure:

Initialize an empty object to store results.

For each object in the array, check if its materialId already exists as a key in the results object.

If it doesn't exist, create a new array for that key.

Push the current object into the appropriate array.

The Code

Here’s the complete implementation:

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

Explanation of the Code:

reduce Function: The reduce function iterates over each item (current) and uses accumulator to build our final result.

Type Declaration: We use Record<string, typeof statisticsOfScrapDeliveriesItems> to define the type of our accumulator, ensuring TypeScript knows what structure we expect.

Results

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

This organization provides a clear structure allowing for streamlined access and better maintainability of your data.

Conclusion

In summary, using TypeScript's reduce method is an excellent approach to transform an array of objects into a more manageable structure based on specific properties. By understanding this technique, you can enhance your data handling capabilities and make your TypeScript programs more efficient.

Try implementing this in your own projects, and enjoy the benefits of organized data access!