Скачать или смотреть How to Sum Array of Objects Values by Multiple Keys in JavaScript

Discover a straightforward method to `sum the values` of objects in an array by multiple keys using JavaScript. Optimize your code for efficiency with this comprehensive guide!
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How to Sum Array of Objects Values by Multiple Keys in JavaScript

When working with arrays of objects in JavaScript, you may find yourself in a situation where you need to sum values of specific keys from objects that share the same identifier. This problem often arises in data manipulation, particularly when consolidating reported data from APIs, aggregating statistics, or even processing user inputs.

The Problem

Let's consider a practical example. You have the following array of objects:

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

The goal here is to sum the values of value and nn for objects that have the same name. The expected output would look like this:

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

The Solution

To correctly sum the values across multiple keys, we can leverage the reduce method. Here’s how to implement this solution step by step.

Step 1: Initialize the Reduction

We'll use reduce to iterate over the array. Inside this method, we’ll maintain an accumulator object that will keep track of the summed values for each unique name.

Step 2: Check for Existing Names

In our reducer function, we first check if we have already encountered the object's name. If it doesn't exist in our accumulator, we will initialize it with the current record.

Step 3: Sum the Relevant Keys

If the name already exists, we need to iterate over our keysToSum array and increment each relevant field accordingly.

The Code

Here's the complete code that implements the above solution:

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

Explanation of the Code

Object Creation: The accumulator obj is a plain object where keys are the names of the products (P1, P2, etc.), and the values are the summed objects.

Copying Record: If the name is encountered for the first time, the object is copied into the accumulator.

Summation: If the name already exists, we iterate over the keys in keysToSum, incrementing each property accordingly.

Final Output: At the end, Object.values is used to convert the accumulated object back into an array format.

Conclusion

This method of summing values not only enables you to handle multiple fields dynamically but also keeps your code versatile and clean. Whether you're dealing with large datasets or small arrays, this approach is efficient and demonstrates the power of JavaScript's array manipulation techniques.

Now you can confidently sum values of multiple keys from objects in arrays in a concise and declarative manner!