全局函数/变量值来自未定义＆＃39;在addEventListener里面

Question

我试图从 addEventListener 中的全局函数/变量中获取JSON对象。但我只是将值设为 undefined ，尽管在​​addEventListener中调用了全局函数。

我应该收到动态创建并存储在变量 colJSON 中的JSON。

function returnJSON() {
         var colSize = 7;//hardcoded.
         var SegTotal;
         var colSTR = '';
         var colJSON;

         $.ajax({
            url: "./myCSV.csv",
            type: "GET",
            async: true,
            dataType: "text",
            success: function (csvd) {

               data = $.csv.toArrays(csvd);
               //data=get(csvd)
               SegTotal= data;

               var seg= 'Segment';
               var strStart= '[';
               var strEnd= ']';
               var strquote= "'";
               var nextline= '\n';
               for(
                     var i= 0; i < SegTotal.length; i++) {
                  var segstr = seg.concat(i + 1);
                  var ARvalue = SegTotal[i] / colSize;
                  var strAR = '';
                  for (var j = 0; j < colSize; j++) {
                     //alert('hello');
                     strAR = strAR.concat(ARvalue).concat(',');
               }

                  colSTR = colSTR.concat(strStart).concat(strquote).concat(segstr).concat(strquote).concat(',').concat(strAR).concat(SegTotal[i]).concat(strEnd).concat(',').concat(nextline);

            }

               alert(colSTR);
               colSTR = strStart.concat(colSTR).concat(strEnd);
               //alert("length of csv data - " +SegTotal.length);
               alert("JSONstring below\n\n" + colSTR);

               //colJSON = JSON.stringify(colSTR);
               colJSON= eval('('+ colSTR+ ')');

               alert(colJSON);
            $('#csvdata').html(colJSON);

         }
      });
         return colJSON;
      }

      document.addEventListener("DOMContentLoaded", function() {

         //var collector=colJSON; //Here is the global variable used
         var collector=returnJSON();
         alert("collectorJSON check here\n" + collector);

         var    container = document.getElementById('collectorPortfolio'), hot;

         hot = new Handsontable(container, {
            data: collector,
            rowHeaders: true,
            contextMenu: true,
            manualColumnResize: true,

            colHeaders: ['TYPE', 'Col1', ' Col2', 'Col3' , 'Col4' ,'Col5','Col6','Col7', 'Total'],
            formulas: true,

            columns: [
               {readOnly: true},
               {readOnly: false},
               {readOnly: false},
               {readOnly: false},
               {readOnly: false},
               {readOnly: false},
               {readOnly: false},
               {readOnly: false},
               {readOnly: true}
            ], 
         });


      });