How to group arrays in JavaScript without reduce() - Matt Smith

"JavaScript now has native support for grouping data with Object.groupBy() and Map.groupBy(). These static methods make grouping expressive, concise, and far more readable, without the need for external libraries or complex reduce() patterns. What are Object.groupBy() and Map.groupBy()? Both of these methods were introduced in ES2024 and allow you to group elements of an array by a key generated from a callback function."

"Map.groupBy() const items = [1.1, 2.3, 2.4, 3.5]; const grouped = Map.groupBy(items, Math.floor); console.log(grouped); // Map { // 1 => [1.1], // 2 => [2.3, 2.4], // 3 => [3.5] // } Because Map.groupBy() can use non-string keys (like numbers or objects), it's more flexible in certain scenarios. Replacing reduce() with groupBy() Before groupBy(), grouping required using reduce() manually: const grouped = items.reduce((acc, item) => {"

ES2024 adds Object.groupBy() and Map.groupBy() as static methods to group array elements by keys produced from a callback. Object.groupBy(array, callback) returns a plain object whose string keys map to arrays of matching elements. Map.groupBy(array, callback) returns a Map that preserves insertion order and supports non-string keys such as numbers or objects. These methods replace common reduce() boilerplate for grouping, producing clearer and more concise code. Example usage includes grouping strings by their first character and numbers by Math.floor. Developers avoid external libraries for basic grouping tasks.

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