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includes

Checks if a value exists in a collection. Supports arrays, strings, objects, Maps, and Sets with optional starting index for arrays and strings.

Usage Scenarios

  • Collection Search: Quickly check if a value exists in various collection types.
  • Data Validation: Verify if required values are present in input data.
  • Conditional Logic: Execute different code paths based on presence of values.

Examples

import { includes } from 'funtool';

// Check array
includes([1, 2, 3], 2); // true
includes([1, 2, 3], 2, 2); // false (starting from index 2)

// Check string
includes('hello world', 'world'); // true
includes('hello world', 'world', 8); // false (starting from index 8)

// Check object values
includes({ a: 1, b: 2 }, 2); // true

// Check Map keys
includes(new Map([['a', 1], ['b', 2]]), 'b'); // true

// Check Set values
includes(new Set([1, 2, 3]), 2); // true

Signature

// Array version
function includes<T>(source: T[], target: T, fromIndex?: number): boolean;

// String version
function includes(source: string, target: string, fromIndex?: number): boolean;

// Object version
function includes(source: Record<string, any>, target: any): boolean;

// Map version
function includes<K, V>(source: Map<K, V>, target: K): boolean;

// Set version
function includes<T>(source: Set<T>, target: T): boolean;

// Generic implementation
function includes(source: any, target: any, fromIndex: number = 0): boolean;

Parameters

  • source (T[] | string | Record<string, any> | Map<K, V> | Set<T>): The collection to search.
  • target (T | string | any | K): The value to search for.
  • fromIndex (number): Optional starting index for arrays/strings (default: 0).

Returns

  • (boolean): True if found, otherwise false.
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