var customerMap=json.customerMap;
var str="[";
for(var i=0;i<customerMap.length;i++)
{
                str+="["+customerMap[i].evaluateDate+","+customerMap[i].grade+'],'
}
str=str.substr(str.length-1);  //去掉最后一个逗号
str+=']';

var customerMap=json.customerMap; 不就得到了json数组了吗？干嘛要拼接