es-toolkit/docs/reference/compat/array/includes.md

includes

::: info This function is only available in es-toolkit/compat for compatibility reasons. It either has alternative native JavaScript APIs or isn’t fully optimized yet.

When imported from es-toolkit/compat, it behaves exactly like lodash and provides the same functionalities, as detailed here. :::

Checks if a specified value exists within a given source, which can be an array, an object, or a string.

The comparison uses SameValueZero to check for inclusion.

Signature

function includes<T>(arr: T[], item: T, fromIndex?: number): boolean;
function includes<T extends Record<string, any>>(obj: T, value: T[keyof T], fromIndex?: number): boolean;
function includes(str: string, substr: string, fromIndex?: number): boolean;

Parameters

• source (T[] | Record<string, any> | string): The source to search in. It can be an array, an object, or a string.
• target (T): The value to search for in the source.
• fromIndex (number): The index to start searching from. If negative, it is treated as an offset from the end of the source.

Returns

(boolean): true if the value is found in the source, false otherwise.

Examples

includes([1, 2, 3], 2); // true
includes({ a: 1, b: 'a', c: NaN }, 'a'); // true
includes('hello world', 'world'); // true
includes('hello world', 'test'); // false