AsyncCallback
意义：
异步操作完成时调用的方法
语法1：
构造异步回调对象
AsyncCallback 异步回调对象名asyncCallback = new AsyncCallback(异步操作完成时调用的方法MyAsyncCallback);
语法2：
定义委托，并进行异步调用，异步调用完成后自动触发
委托类型Action fn委托名 = Run委托定义;
???????????委托名fn.BeginInvoke(异步回调对象名asyncCallback );
示例：
using System;namespace Examples.AdvancedProgramming.AsynchronousOperations{ ???public class UseDelegateForAsyncCallback ???{ ???????delegate string MethodDelegate(int iCallTime); ???????public static void Main() ???????{ ???????????MethodDelegate dlgt = (m)=> ????????????{ ???????????????return "你输入的数字是"+m; ???????????}; ???????????AsyncCallback asyncCallback = new AsyncCallback(MyAsyncCallback); ??????????????????????Action fn = Run; ???????????fn.BeginInvoke(asyncCallback,null); ???????} ???????private static void MyAsyncCallback(IAsyncResult ar) ???????{ ???????????Console.WriteLine("异步调用"); ???????????Console.ReadLine(); ???????} ???????public static void Run() ???????{ ???????} ???}}/// ?控制台输出结果：/// ????你输入的数字是:5/// ????异步调用
来自：https://www.cnblogs.com/licin/p/8274405.html
JS Async Callback
原文地址：https://www.cnblogs.com/weinixiong/p/10054536.html