partition

Returns a tuple that splits an array into two groups based on a condition.

const [truthy, falsy] = partition(arr, isInTruthy);

Reference

partition(arr, isInTruthy)

Use partition when you want to separate elements in an array into two groups based on a specific condition. It separates elements for which the condition function returns true and elements for which it returns false into different arrays.

import { partition } from 'es-toolkit/array';

// Split a number array into even and odd numbers.
const numbers = [1, 2, 3, 4, 5, 6];
const [evens, odds] = partition(numbers, x => x % 2 === 0);
// evens: [2, 4, 6]
// odds: [1, 3, 5]

// Split an object array by a specific condition.
const users = [
  { name: 'Alice', active: true },
  { name: 'Bob', active: false },
  { name: 'Charlie', active: true },
];
const [activeUsers, inactiveUsers] = partition(users, user => user.active);
// activeUsers: [{ name: 'Alice', active: true }, { name: 'Charlie', active: true }]
// inactiveUsers: [{ name: 'Bob', active: false }]

It returns two empty arrays for an empty array.

import { partition } from 'es-toolkit/array';

const [truthy, falsy] = partition([], x => x > 0);
// truthy: []
// falsy: []

Parameters

• arr (T[]): The array to split into two groups.
• isInTruthy ((value: T) => boolean): A condition function that determines whether each element should be included in the first array (truthy) or the second array (falsy).

Returns

([truthy: T[], falsy: T[]]): A tuple consisting of two arrays. The first array contains elements for which the condition is true, and the second array contains elements for which the condition is false.