import { AxiosResponse } from "axios";
/**
 * Returns true if the specified value is not undefined.
 *
 * @param val Variable to test.
 * @return Whether variable is defined.
 */
export declare function isDef(val: any): boolean;
export declare function isEmptyString(val: string): boolean;
export declare function isNotEmptyString(val: string): boolean;
export declare function isNotEmpty(val: any): boolean;
/**
 * Compare function for string values by field.
 * @return {function(*, *):number}
 */
export declare function compareStringByField(fieldName: string): (a: any, b: any) => any;
/**
 * Number of digits greater than argument.
 *
 * Gets count of digits and compare with argument.
 * Note: this works only with integers, not floats.
 */
export declare function numberOfDigitsGreaterThan(val: number, digitsCount: number): boolean;
/**
 * Extract `obj` from directual response.
 */
export declare function extractResponseObject(response: object): object;
/**
 * Extract array result from directual response.
 */
export declare function extractResponseArray(response: object): any[];
/**
 * Extract data from axios response.
 * @param {AxiosResponse} response
 * @return {*}
 */
export declare function extractResponseData(response: AxiosResponse): any;
/**
 * Convert string to array.
 */
export declare function stringToArray(val: string): any[];