/**
 * function tests is given string a valid JSON, or not
 * Examples:
 *      isJSON('') -> false
 *      isJSON(null) -> false
 *      isJSON('{}') -> true
 *      isJSON('{"1": invalid json') -> false
 */
export declare function isJSON(str: string): boolean;
export declare function isJSONObject(str: string): boolean;
export declare function isInt(val: string | number): boolean;
/**
 * strict check if string is valid float
 * Example:
 * 		isFloat('1.2') -> true
 * 		isFloat('1') -> true
 * 		isFloat('1,2') -> true
 * 		isFloat('1.2b') -> false
 * 		isFloat('1.2 ') -> false
 */
export declare function isFloat(val: string): boolean;