nodejs 异步io 解决for循环最佳方案

nodejs 众所周知单线程，异步io。

模型图如下：

对于for循环来说写起来非常麻烦，曾尝试过闭包，es6，asnyc。

最终选择了使用 eventproxy，具体是什么东西，大家可以百度。用起来很方便，下面上一简单个人亲测代码示例：

var eventproxy = require('eventproxy');

var ep = new eventproxy();

               // list 结果集合

                ep.after('get_attendance_teacher', result.length, function (list) {
                   
                    res.json(list);
                });
                //for循环 io
                for (var i = 0; i < result.length; i++) {
                    var queryAttendance ={};
                    queryAttendance = {'userId':result[i]._id,"time" : {$gt:startDate, $lt:endDate}};
                    Attendance.find(queryAttendance, function(err, resultAttendance) {
                        if (err) {
                            console.log("db get attendance err::", err);
                            return;
                        }
                        ep.emit('get_attendance_teacher', resultAttendance);

                    }).sort({"name":1,'time':timeSort});

                }
            }

双层for循环 简单demo

var arr = [{name:'Jack'}, {name:'Mike'}];
            async.map(arr, function(item1, callback1) {
                    
                    var arr2 = [{name:'111'}, {name:'222'}];
                    async.map(arr2, function(item2, callback2) {
                        callback2(null, item1.name+item2.name+'!!!');
                    }, function(err,abc) {
                        console.log(111111111)
                        console.log(abc)
                        // jack111 jack222   
                        // 11111111
                        // mike111 mike222
                        callback1(null, abc);
                    });

            }, function(err,resultAll) {
                console.log(2222222)
                console.log(resultAll)
                // jack111 jack222   mike111 mike222
            });