import type { Key } from 'react';
export declare const checkType: (val: unknown, tag: string) => boolean;
export declare const isPlainObject: (val: unknown) => val is Record<Key, any>;
export declare const isObject: (val: unknown) => val is object;
export declare const isUndefined: (val: unknown) => val is undefined;
export declare const isNull: (val: unknown) => val is null;
export declare const isNil: (val: unknown) => val is null | undefined;
export declare const isNumber: (val: unknown) => val is number;
export declare const isBoolean: (val: unknown) => val is boolean;
export declare const isString: (val: unknown) => val is string;
export declare const isArray: <T = any>(val: unknown) => val is T[];
export declare const isFunction: (val: unknown) => val is Function;
export declare const isDate: (val: unknown) => val is Date;