Skip to main content
Using Deno in production at your company? Earn free Deno merch.
Give us feedback
Module

std/collections/max_by.ts

The Deno Standard Library
Go to Latest
File
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
/** * Returns the first element that is the largest value of the given function or * undefined if there are no elements. * * @example * ```ts * import { maxBy } from "https://deno.land/std@$STD_VERSION/collections/max_by.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts"; * * const people = [ * { name: "Anna", age: 34 }, * { name: "Kim", age: 42 }, * { name: "John", age: 23 }, * ]; * * const personWithMaxAge = maxBy(people, (i) => i.age); * * assertEquals(personWithMaxAge, { name: "Kim", age: 42 }); * ``` */export function maxBy<T>( array: Iterable<T>, selector: (el: T) => number,): T | undefined;/** * Returns the first element that is the largest value of the given function or * undefined if there are no elements. * * @example * ```ts * import { maxBy } from "https://deno.land/std@$STD_VERSION/collections/max_by.ts"; * * const people = [ * { name: "Anna" }, * { name: "Kim" }, * { name: "John" }, * ]; * * const personWithMaxName = maxBy(people, (i) => i.name); * ``` */export function maxBy<T>( array: Iterable<T>, selector: (el: T) => string,): T | undefined;/** * Returns the first element that is the largest value of the given function or * undefined if there are no elements. * * @example * ```ts * import { maxBy } from "https://deno.land/std@$STD_VERSION/collections/max_by.ts"; * import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts"; * * const people = [ * { name: "Anna", age: 34n }, * { name: "Kim", age: 42n }, * { name: "John", age: 23n }, * ]; * * const personWithMaxAge = maxBy(people, (i) => i.age); * * assertEquals(personWithMaxAge, { name: "Kim", age: 42n }); * ``` */export function maxBy<T>( array: Iterable<T>, selector: (el: T) => bigint,): T | undefined;/** * Returns the first element that is the largest value of the given function or * undefined if there are no elements. * * @example * ```ts * import { maxBy } from "https://deno.land/std@$STD_VERSION/collections/max_by.ts"; * * const people = [ * { name: "Anna", startedAt: new Date("2020-01-01") }, * { name: "Kim", startedAt: new Date("2021-03-01") }, * { name: "John", startedAt: new Date("2020-03-01") }, * ]; * * const personWithLastStartedAt = maxBy(people, (i) => i.startedAt); * ``` */export function maxBy<T>( array: Iterable<T>, selector: (el: T) => Date,): T | undefined;export function maxBy<T>( array: Iterable<T>, selector: | ((el: T) => number) | ((el: T) => string) | ((el: T) => bigint) | ((el: T) => Date),): T | undefined { let max: T | undefined = undefined; let maxValue: ReturnType<typeof selector> | undefined = undefined;
for (const current of array) { const currentValue = selector(current);
if (maxValue === undefined || currentValue > maxValue) { max = current; maxValue = currentValue; } }
return max;}