/**
 * Type Guards
 *
 * Runtime type checking utilities for type-safe code.
 * Following PostHog's pattern from @posthog/core.
 */
/**
 * Check if value is a string
 */
export declare function isString(x: unknown): x is string;
/**
 * Check if value is a number (and not NaN)
 */
export declare function isNumber(x: unknown): x is number;
/**
 * Check if value is a boolean
 */
export declare function isBoolean(x: unknown): x is boolean;
/**
 * Check if value is undefined
 */
export declare function isUndefined(x: unknown): x is undefined;
/**
 * Check if value is null
 */
export declare function isNull(x: unknown): x is null;
/**
 * Check if value is null or undefined
 */
export declare function isNullish(x: unknown): x is null | undefined;
/**
 * Check if value is an array
 */
export declare function isArray(x: unknown): x is unknown[];
/**
 * Check if value is a plain object (not null, not array)
 */
export declare function isObject(x: unknown): x is Record<string, unknown>;
/**
 * Check if value is a function
 */
export declare function isFunction(x: unknown): x is (...args: unknown[]) => unknown;
/**
 * Check if value is a Date object
 */
export declare function isDate(x: unknown): x is Date;
/**
 * Check if value is a valid element
 */
export declare function isElement(x: unknown): x is Element;
/**
 * Check if value is a valid HTMLElement
 */
export declare function isHTMLElement(x: unknown): x is HTMLElement;
/**
 * Check if value is empty (null, undefined, empty string, empty array, empty object)
 */
export declare function isEmpty(x: unknown): boolean;
/**
 * Check if value is a non-empty string
 */
export declare function isNonEmptyString(x: unknown): x is string;
/**
 * Check if value is a positive number
 */
export declare function isPositiveNumber(x: unknown): x is number;
/**
 * Check if value is a RegExp
 */
export declare function isRegExp(x: unknown): x is RegExp;