nested for loop in node js with asynchronous

I have userCurrentContainer = [[],[{"1":"xyz"},{"2":"abc"}],[{"1":"xyz"}],[]]

I to want to group by key so the output will look like: { 1: xyzxyz, 2: abc}

I am using async Library. I understood grouping logic .. but my problem is when everything done then i will callback.. but it is before calling..

function grupbyContainerId(userCurrentContainer,callback){
            var track=0;
            var temp=new Array();
            async.eachSeries(userCurrentContainer, function (key,callback1) {
                track=track+1

                if(key.length>0){
                    var innertrack=0;
                    async.eachSeries(key, function (key1,callback2) {
                         innertrack=innertrack+1
                         //logic here 

                         if(track>=userCurrentContainer.length&&innertrack,key.length>=key.length){
                            console.log("if calledd ---------->");
                            callback(null,temp)
                         }

                        callback2();
                    })
                }

                callback1();

            });

        }

via Aakash Kag