guardz/dist/typeguards/isNegativeInteger.d.ts

A simple and lightweight TypeScript type guard library for runtime type validation.

import type { NegativeInteger } from '../types/NegativeInteger';
import type { TypeGuardFn } from './isType';
/**
 * Checks if a value is a negative integer (less than 0 and a whole number).
 *
 * Note: This excludes zero, positive numbers, decimals, NaN, and Infinity.
 *
 * @param value - The value to check
 * @param config - Optional configuration for error handling
 * @returns True if the value is a negative integer, false otherwise
 *
 * @example
 * ```typescript
 * import { isNegativeInteger } from 'guardz';
 *
 * console.log(isNegativeInteger(-1)); // true
 * console.log(isNegativeInteger(-42)); // true
 * console.log(isNegativeInteger(-100)); // true
 * console.log(isNegativeInteger(0)); // false (zero is not negative)
 * console.log(isNegativeInteger(1)); // false
 * console.log(isNegativeInteger(-1.5)); // false (not an integer)
 * console.log(isNegativeInteger(NaN)); // false
 * console.log(isNegativeInteger("-5")); // false
 *
 * // With type narrowing
 * const data: unknown = getUserInput();
 * if (isNegativeInteger(data)) {
 *   // data is now typed as NegativeInteger
 *   console.log(`Debt amount: ${Math.abs(data)}`); // Safe to use as negative integer
 * }
 * ```
 */
export declare const isNegativeInteger: TypeGuardFn<NegativeInteger>;