import { ListHandlerType, LoggerTypes } from '../interfaces';
/** noop function */
export declare const noop: <T = any>(x: T) => T;
/**
 * is empty object (null, undefined or empty string)
 * @param obj
 */
export declare function isEmpty(obj: any): boolean;
/**
 * safety parse JSON
 * @param str
 */
export declare function parseJSON<T = Record<string, any>>(str: string): T;
/**
 * 返回时间戳: HH:mm:ss.LLL
 */
export declare const timestamp: (d?: Date) => string;
/** 打印控制台日志 */
export declare const logger: LoggerTypes;
/**
 * 睡眠一定时间
 * @param mill milliseconds
 */
export declare function sleep(mill: number): Promise<void>;
/**
 * 返回一个整数随机数 [min, max] (包含 min and max)
 */
export declare function random(min?: number, max?: number): number;
/**
 * JSON 序列化
 * @param params
 * @param holdEmpty 是否保留空参数
 * @param listHandler 数组处理方式, 默认 `REPEAT`
 * - `TILE`: 平铺 `a[]=1&a[]=2`
 * - `REPEAT`: 重复 `a=1&a=2`
 * - `JOIN`: 用逗号连接 `a=1,2`
 */
export declare function serialize(params: Record<string, any> | string, holdEmpty?: boolean, listHandler?: ListHandlerType): string;
/**
 * 从一个 JSON 对象中解析剔除无用的属性，返回指定的属性
 * @param obj
 * @param keys 要保留的属性
 */
export declare function keepProps<T = Record<string, any>>(obj: any, keys: Array<keyof T>): T;
/**
 * 将 JSON 转化为 formData
 * @param obj JSON data
 */
export declare function json2FormData(obj?: Record<string, any>): FormData;