为什么我不能将数组分配给jqgrid列?

我编写了以下代码以从数组生成列和列模型，有趣的是，当我在jqgrid中对生成的数组进行硬编码(如下所示)时，它会生成列，但是将数组放入变量中然后将其分配给colModel它不会生成列.为什么会这样，我该如何解决?

i have wrriten the following code to generate columns and column model from an array, whats funny is when i hard code the generated array in jqgrid like below it generates teh columns but when put the array to a variable and then assign it to colModel it wont generate the columns. why is that and how do i fix this?

完整的代码在底部

通过 http://www.trirand.com/blog/jqgrid/使用JQGrid jqgrid.html

" https://cdnjs .cloudflare.com/ajax/libs/jqgrid/4.6.0/js/jquery.jqGrid.min.js "

以下是硬编码代码:

//hard coding the array
    $('#myGrid').jqGrid({
        datatype: "local",
        height: 250,
        //colNames:modelArr,
        colModel:[{name:' 9/10/2014'}, {name:' 1/1/2014'}, {name:' 2/10/2014'}],
        viewrecords: true,
        multiselect: true,
        caption: "Manipulating Array Data"
    });

这是完整的代码:

    var colsArray =[];
    var modelArr = [];

    $.ajax({
        url:'http://localhost:53721/Home/GetPurchases',
        dataType:'json',
        success:function(data){
            colsArray=data;

            var str='';

            if(data.length > 0 ){
                str = data[0].PurchaseDates;
                console.log(str);
               colsArray = str.split(',');
            }


            for(var i=0; i < colsArray.length;i++){
                var tmp = {name:colsArray[i]};
                modelArr[i]=tmp;
            }

            //console.log(JSON.stringify(modelArr));

        },
        error:function(){}

    });

    var d1 = JSON.stringify(modelArr);
    console.log(d1);

    $('#myGrid').jqGrid({
        datatype: "local",
        height: 250,
        //colNames:modelArr,
        colModel:[modelArr],         //[{name:' 9/10/2014'}, {name:' 1/1/2014'}, {name:' 2/10/2014'}],
        viewrecords: true,
        multiselect: true,
        caption: "Manipulating Array Data"
    });