maxBy

Returns the element of an array with the greatest derived key, computed by keyFn. Unlike max, which only compares raw numbers, maxBy returns the item itself, not the key. On a tie, the earliest element with that key wins. null and undefined are treated as empty arrays and return undefined.

Available since v3.0.8

Import

import { maxBy } from '@helpers4/array';
// or, from the all-in-one package (same code, one install):
import { maxBy } from 'helpers4/array';

Signature

maxBy<T>(array: readonly T[] | null | undefined, keyFn: function): T | undefined

Parameters

Parameter	Type	Description
array	readonly T[] | null | undefined	Array of items
keyFn	function	Derives the comparable key for an item

Returns

T | undefined — The element with the greatest key, or undefined for empty arrays, null, undefined

Examples

Pick the item with the greatest derived value

Unlike max(), maxBy() returns the whole item, chosen by a key derived from it.

maxBy(
  [{ name: 'a', size: 3 }, { name: 'b', size: 9 }, { name: 'c', size: 1 }],
  (item) => item.size,
)
// => { name: 'b', size: 9 }

Empty array returns undefined

There is no maximum to return for an empty array.

maxBy([], (item: { size: number }) => item.size)
// => undefined

Source

View source on GitHub