How do I group an array of objects in JavaScript and sum a field?
import { groupBy } from ' groupjs_by ' ; const byStatus = groupBy ( orders , ' status ' ) . sum ( ' revenue ' , ' amount ' ) . count ( ' orders ' ) . toArray (); bash npm install groupjs_by Every modern article tells you to use native Object.groupBy(). The problem? It stops halfway. Native bucketing only splits your data into isolated arrays. It leaves you stuck writing messy reduce() loops just…
The article explains how to group a JavaScript array of objects and sum a specific field within each group. While modern tutorials recommend using native Object.groupBy(), this approach leaves developers writing additional reduce() loops to perform basic calculations like sum, average, or count on the grouped data.
The author introduces groupjs_by, a library that combines grouping and aggregation into a single, efficient operation. By using the groupBy() function from groupjs_by, you can easily sum a field (like revenue or amount) for each group derived from a specified key (such as status) in the input array of objects.
The article also provides an example of multi-key grouping, where you can specify an array of keys to group by simultaneously. This eliminates the need for nested loops and simplifies the code for creating chart-ready rows.
To use groupjs_by, simply install it via npm and then use the groupBy() function in your code. The library handles zero dependencies, offers a single-pass aggregation for large datasets, and automatically skips null, undefined, or non-numeric values to avoid NaN errors.
The full documentation, TypeScript examples, and performance benchmarks are available on the groupjs_by GitHub repository.
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