import { Dayjs } from "dayjs";
import { ReactNode } from "react";
export declare function isDayjs(time: any): time is Dayjs;
export declare function isArray(obj: any): obj is any[];
export declare function isObject(obj: any): obj is {
    [key: string]: any;
};
export declare function isEmptyObject(obj: any): boolean;
export declare function isPromise(obj: any): obj is {
    [key: string]: any;
};
export declare function isString(obj: any): obj is string;
export declare function isNumber(obj: any): obj is number;
export declare function isFile(obj: any): obj is File;
export declare function isFunction<T extends Function = Function>(value: any): value is T;
export declare function isUndefined(obj: any): obj is undefined;
export declare function isNull(obj: any): obj is null;
export declare function isNullOrUndefined(obj: any): boolean;
export declare const isServerRendering: boolean;
/** merge multiple children to a string node */
export declare const isSingleNode: (child: ReactNode) => boolean;