@monstermann/fn/dist/object/is.d.ts

A utility library for TypeScript.

import { AllUnionFields, Simplify } from "type-fest";

//#region src/object/is.d.ts
type PropIs<T extends object, U, V> = T extends unknown ? U extends keyof T ? V extends T[U] ? Simplify<T & Record<U, V>> : never : never : never;
/**
 * `is(target, key, value)`
 *
 * Checks if the `key` property of `target` object is equal to the specified `value` using strict equality.
 *
 * ```ts
 * is({ a: 1, b: 2 }, "a", 1); // true
 * is({ a: 1, b: 2 }, "a", 2); // false
 * ```
 *
 * ```ts
 * pipe({ a: 1, b: 2 }, is("a", 1)); // true
 * pipe({ a: 1, b: 2 }, is("a", 2)); // false
 * ```
 */
declare const is: {
  <T extends object, U extends keyof AllUnionFields<T>, const V extends AllUnionFields<T>[U]>(key: U, value: V): (target: T) => target is PropIs<T, U, V>;
  <T extends object, U extends keyof AllUnionFields<T>, const V extends AllUnionFields<T>[U]>(target: T, key: U, value: V): target is PropIs<T, U, V>;
};
//#endregion
export { is };