Creating An Array Of Cumulative Sum In Javascript

Have you ever needed to calculate a running total or cumulative sum in JavaScript? Well, you're in luck because in this article, we'll walk you through how to create an array of cumulative sums using JavaScript.

To start off, let's clarify what a cumulative sum is. A cumulative sum is the sum of a sequence of values up to a certain point. For example, in an array `[1, 2, 3, 4, 5]`, the cumulative sum array would be `[1, 3, 6, 10, 15]`, where each element is the sum of all previous elements in the original array.

Here's a simple and efficient way to create an array of cumulative sums in JavaScript:

const originalArray = [1, 2, 3, 4, 5];
const cumulativeSumArray = originalArray.reduce((acc, curr, index) => {
  acc[index] = (acc[index - 1] || 0) + curr;
  return acc;
}, []);

In this code snippet, we first define our original array of numbers. Then, we use the `reduce` method on the original array. The `reduce` method iterates over each element in the originalArray and accumulates the sum in the cumulativeSumArray array.

Let's break down what's happening in the `reduce` method:

- `acc` is the accumulator that stores the cumulative sums as we iterate over the elements of the original array.
- `curr` is the current element from the original array.
- `index` is the index of the current element in the original array.

The expression `(acc[index - 1] || 0)` calculates the sum of the previous elements in the original array. If there are no previous elements (i.e., if `index` is 0), it defaults to 0.

By adding the current element `curr` to the sum of the previous elements, we calculate the cumulative sum for each element in the original array and store it in the `cumulativeSumArray`.

After running this code snippet, `cumulativeSumArray` will contain `[1, 3, 6, 10, 15]`, which is the cumulative sum of `[1, 2, 3, 4, 5]`.

Creating an array of cumulative sums comes in handy in various scenarios, such as calculating running totals, analyzing trends over time, or processing financial data.

So, whether you're working on data analysis, financial modeling, or any other project that requires calculating cumulative sums in JavaScript, you now have a straightforward method to create an array of cumulative sums efficiently.

Give it a try in your next JavaScript project and see how easily you can implement this useful technique!