isSubset

Checks if one array is a subset of another array.

const result = isSubset(superset, subset);

Reference

isSubset(superset, subset)

Use isSubset when you want to check if all elements of one array are contained in another array. This is useful for verifying subset relationships or checking if permissions, features, tags, etc., are within the allowed range.

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

// Check subset in number arrays
const numbers = [1, 2, 3, 4, 5];
const subset = [2, 3, 4];
isSubset(numbers, subset);
// Returns: true

// Check subset in string arrays
const permissions = ['read', 'write', 'delete', 'admin'];
const userPermissions = ['read', 'write'];
isSubset(permissions, userPermissions);
// Returns: true

// When it's not a subset
const colors = ['red', 'blue', 'green'];
const invalidColors = ['red', 'yellow'];
isSubset(colors, invalidColors);
// Returns: false

Special cases are also handled correctly.

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

// An empty array is always a subset
const anyArray = [1, 2, 3];
const emptyArray: number[] = [];
isSubset(anyArray, emptyArray);
// Returns: true

// The same array is a subset of itself
const same = ['a', 'b', 'c'];
isSubset(same, same);
// Returns: true

// Works correctly even with duplicate elements
const withDuplicates = [1, 2, 2, 3];
const duplicateSubset = [2, 2];
isSubset(withDuplicates, duplicateSubset);
// Returns: true

Parameters

• superset (readonly T[]): The superset array that may contain all elements of the subset.
• subset (readonly T[]): The subset array to check if it's contained in the superset.

Returns

(boolean): Returns true if all elements of the subset are contained in the superset, otherwise returns false.