ts-extras
Version:
Essential utilities for TypeScript projects
22 lines (16 loc) • 683 B
TypeScript
/**
An alternative to `Array#includes()` that properly acts as a type guard.
It was [rejected](https://github.com/microsoft/TypeScript/issues/26255#issuecomment-748211891) from being done in TypeScript itself.
@example
```
import {arrayIncludes} from 'ts-extras';
const values = ['a', 'b', 'c'] as const;
const valueToCheck: unknown = 'a';
if (arrayIncludes(values, valueToCheck)) {
// We now know that the value is of type `typeof values[number]`.
}
```
@category Improved builtin
@category Type guard
*/
export declare function arrayIncludes<Type extends SuperType, SuperType = unknown>(array: Type[] | readonly Type[], item: SuperType, fromIndex?: number): item is Type;