es-toolkit/dist/array/maxBy.js

A state-of-the-art, high-performance JavaScript utility library with a small bundle size and strong type annotations.

//#region src/array/maxBy.ts
/**
* Finds the element in an array that has the maximum value when applying
* the `getValue` function to each element.
*
* @template T - The type of elements in the array.
* @param items The array of elements to search.
* @param getValue A function that selects a numeric value from each element.
* @returns The element with the maximum value as determined by the `getValue` function,
* or `undefined` if the array is empty.
* @example
* maxBy([{ a: 1 }, { a: 2 }, { a: 3 }], x => x.a); // Returns: { a: 3 }
* maxBy([], x => x.a); // Returns: undefined
* maxBy([3, NaN, 1], x => x); // Returns: NaN (NaN propagates, matching Math.max)
* maxBy(
*   [
*     { name: 'john', age: 30 },
*     { name: 'jane', age: 28 },
*     { name: 'joe', age: 26 },
*   ],
*   x => x.age
* ); // Returns: { name: 'john', age: 30 }
*/
function maxBy(items, getValue) {
	if (items.length === 0) return;
	let maxElement = items[0];
	let max = -Infinity;
	for (let i = 0; i < items.length; i++) {
		const element = items[i];
		const value = getValue(element, i, items);
		if (Number.isNaN(value)) return element;
		if (value > max) {
			max = value;
			maxElement = element;
		}
	}
	return maxElement;
}
//#endregion
exports.maxBy = maxBy;