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Array Utilities

A collection of functions for handling arrays with type-safety and efficiency. Includes chunking, deduplication, flattening, grouping, sorting, partitioning, and more. All methods are fully typed.

API Summary​

Function Documentation & Usage Examples​

chunk()​

Splits an array into chunks of the specified size.

Method Signature:

function chunk<T>(array: T[], size: number): T[][];

Parameters:

  • array: The input array to be chunked.
  • size: The size of each chunk.

Returns:

  • An array of chunks, each containing up to size elements.

Examples:

import { chunk } from '@catbee/utils';

chunk([1, 2, 3, 4, 5], 2); // [[1, 2], [3, 4], [5]]

unique()​

Removes duplicate items from an array, optionally by a key function.

Method Signature:

function unique<T>(array: T[], keyFn?: (item: T) => unknown): T[];

Parameters:

  • array: The input array to remove duplicates from.
  • keyFn: An optional function to determine the key for each item.

Returns:

  • A new array with unique items. Does not mutate the original array.

Examples:

import { unique } from '@catbee/utils';

unique([1, 2, 2, 3, 1]); // [1, 2, 3]
unique(users, user => user.id); // [{ id: 1, ... }, { id: 2, ... }]

flattenDeep()​

Deeply flattens a nested array.

Method Signature:

function flattenDeep<T>(array: any[]): T[];

Parameters:

  • array: The input array to deeply flatten.

Returns:

  • A new flattened array of type T[]. Does not mutate the original array.

Examples:

import { flattenDeep } from '@catbee/utils';

flattenDeep([1, [2, [3, [4]], 5]]); // [1, 2, 3, 4, 5]

random()​

Returns a random element from an array.

Method Signature:

function random<T>(array: T[]): T | undefined;

Parameters:

  • array: The input array to select a random element from.

Returns:

  • A random element of type T or undefined if the array is empty.

Examples:

import { random } from '@catbee/utils';

random(['a', 'b', 'c']); // 'a' or 'b' or 'c'

groupBy()​

Groups array items by a key or function.

Method Signature:

function groupBy<T>(array: T[], key: keyof T): Record<string, T[]>;
function groupBy<T, K extends string | number | symbol>(array: T[], keyFn: (item: T) => K): Record<K, T[]>;
function groupBy<T>(array: T[], keyOrFn: keyof T | ((item: T) => string | number | symbol)): Record<string | number | symbol, T[]>;

Parameters:

  • array: The input array to group items from.
  • keyOrFn: The key or function to group items by.

Returns:

  • An object where keys are the group identifiers and values are arrays of grouped items.

Examples:

import { groupBy } from '@catbee/utils';

const users = [
  { name: 'Alice', role: 'admin' },
  { name: 'Bob', role: 'user' },
  { name: 'Charlie', role: 'admin' }
];
groupBy(users, 'role'); // { admin: [...], user: [...] }
groupBy(users, user => user.name[0]); // { A: [...], B: [...], ... }

shuffle()​

Shuffles array elements randomly.

Method Signature:

function shuffle<T>(array: T[]): T[];

Parameters:

  • array: The input array to shuffle.

Returns:

  • A new shuffled array of type T[]. Does not mutate the original array.

Examples:

import { shuffle } from '@catbee/utils';

shuffle([1, 2, 3, 4]); // [3, 1, 4, 2] (order will vary)

pluck()​

Extracts values for a given key from an array of objects.

Method Signature:

function pluck<T, K extends keyof T>(array: T[], key: K): T[K][];

Parameters:

  • array: The input array to pluck values from.
  • key: The key to pluck values for.

Returns:

  • An array of plucked values.

Examples:

import { pluck } from '@catbee/utils';

const users = [{ name: 'Alice' }, { name: 'Bob' }];
pluck(users, 'name'); // ['Alice', 'Bob']

difference()​

Returns elements in array a not present in array b.

Method Signature:

function difference<T>(a: T[], b: T[]): T[];

Parameters:

  • a: The first array to compare.
  • b: The second array to compare.

Examples:

import { difference } from '@catbee/utils';

difference([1, 2, 3, 4], [2, 4]); // [1, 3]

intersect()​

Returns elements common to both arrays.

Method Signature:

function intersect<T>(a: T[], b: T[]): T[];

Parameters:

  • a: The first array to compare.
  • b: The second array to compare.

Examples:

import { intersect } from '@catbee/utils';

intersect([1, 2, 3], [2, 3, 4]); // [2, 3]

mergeSort()​

Sorts array by key or function using merge sort.

Method Signature:

function mergeSort<T>(array: T[], key: string | ((item: T) => any), direction?: 'asc' | 'desc'): T[];

Parameters:

  • array: The input array to sort.
  • key: The key or function to sort by.
  • direction: The sort direction, either "asc" or "desc".

Returns:

  • A new sorted array of type T[]. Does not mutate the original array.

Examples:

import { mergeSort } from '@catbee/utils';

const items = [{ value: 3 }, { value: 1 }, { value: 2 }];
mergeSort(items, item => item.value); // [{ value: 1 }, { value: 2 }, { value: 3 }]
mergeSort(items, item => item.value, 'desc'); // [{ value: 3 }, { value: 2 }, { value: 1 }]

zip()​

Combines multiple arrays element-wise.

Method Signature:

function zip<T>(...arrays: T[][]): T[][];

Parameters:

  • arrays: The input arrays to combine.

Returns:

  • A new array of type T[][]. Does not mutate the original arrays.

Examples:

import { zip } from '@catbee/utils';

zip([1, 2], ['a', 'b'], [true, false]); // [[1, 'a', true], [2, 'b', false]]

partition()​

Splits array into two arrays based on a predicate function.

Method Signature:

function partition<T>(array: T[], predicate: (item: T, index: number, array: T[]) => boolean): [T[], T[]];

Parameters:

  • arrays: The input arrays to combine.
  • predicate: A function that returns true to include the item in the first array.
    • item: The current item being processed.
    • index: The index of the current item.
    • array: The original array being processed.

Returns:

  • A new array of type T[][]. Does not mutate the original arrays.

Examples:

import { partition } from '@catbee/utils';

partition([1, 2, 3, 4], n => n % 2 === 0); // [[2, 4], [1, 3]]

range()​

Creates an array of numbers in a range.

Method Signature:

function range(start: number, end: number, step?: number): number[];

Parameters:

  • start: The starting number of the range (inclusive).
  • end: The ending number of the range (exclusive).
  • step: The increment between numbers in the range (default is 1).

Returns:

  • An array of numbers in the specified range.

Examples:

import { range } from '@catbee/utils';

range(0, 5); // [0, 1, 2, 3, 4]
range(2, 10, 2); // [2, 4, 6, 8]

take()​

Takes the first n elements from an array.

Method Signature:

function take<T>(array: T[], n?: number): T[];

Parameters:

  • array: The input array to take elements from.
  • n: The number of elements to take (default is 1).

Returns:

  • A new array containing the first n elements. Does not mutate the original array.

Examples:

import { take } from '@catbee/utils';

take([1, 2, 3, 4], 2); // [1, 2]

takeWhile()​

Takes elements from array while predicate is true.

Method Signature:

function takeWhile<T>(array: T[], predicate: (item: T, index: number) => boolean): T[];

Parameters:

  • array: The input array to take elements from.
  • predicate: A function that returns true to keep taking elements.
    • item: The current item being processed.
    • index: The index of the current item.

Returns:

  • A new array containing the leading elements that satisfy the predicate. Does not mutate the original array

Examples:

import { takeWhile } from '@catbee/utils';

takeWhile([1, 2, 3, 2, 1], n => n < 3); // [1, 2]

compact()​

Removes falsy values from an array.

Method Signature:

function compact<T>(array: T[]): NonNullable<T>[];

Parameters:

  • array: The input array to compact.

Returns:

  • A new array with all falsy values removed. Does not mutate the original array.

Examples:

import { compact } from '@catbee/utils';

compact([0, 1, false, 2, '', 3, null, undefined]); // [1, 2, 3]

countBy()​

Counts occurrences by key or function.

Method Signature:

function countBy<T>(array: T[], keyFn: (item: T) => string | number | symbol): Record<string, number>;

Parameters:

  • array: The input array to count occurrences from.
  • keyFn: A function that returns the key to count by.

Returns:

  • An object where keys are the counted identifiers and values are their counts.

Examples:

import { countBy } from '@catbee/utils';

countBy(['cat', 'dog', 'cat'], pet => pet); // { cat: 2, dog: 1 }
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