给datagrid的日期格式化成年月日

$('#infos').datagrid({
            title:'系统版本列表',
            iconCls:'icon-view',
            method:'POST',
            singleSelect:false,
            fit : true,
            border : true,
            fitColumns:true,
            striped: true,
            collapsible:true,
            url:mUrl.queryVersionByConditionPaging,
            sortName: 'versionId',
            sortOrder: 'desc',
            remoteSort: true,
            idField:'versionId',
            queryParams:{},
            pagination:true,
            rownumbers:true,
            pageSize : 15,
            pageList : [15, 30, 45, 60, 75,90,100,150],
            frozenColumns:[[
                {field:'ck',checkbox:true},
                {title:'versionId',field:'versionId',width:10,sortable:true,hidden:true}
            ]],
            columns:[[
                {field:'productCode',title:'产品编号',width:80},
                {field:'versionCode',title:'版本编号',width:100},
                {field:'upgradeTime',title:'升级时间',width:100,
                     formatter : function(value){
                            var date = new Date(value);
                            var y = date.getFullYear();
                            var m = date.getMonth() + 1;
                            var d = date.getDate();
                            return y + '-' +m + '-' + d;
                        }},
                {field:'status',title:'版本状态',width:100,
                    formatter:function(value){
                        <c:forEach var="dataDic" items="${requestScope.VERSION_TYPE}">
                            if(value=='${dataDic.dicItemValue}'){
                                return '${dataDic.dicItemName}';
                            }
                        </c:forEach>
                    }},
                {field:'upgradeWay',title:'升级方式',width:80,
                    formatter:function(value){
                        <c:forEach var="dataDic" items="${requestScope.UPGRADEWAY_TYPE}">
                            if(value=='${dataDic.dicItemValue}'){
                                return '${dataDic.dicItemName}';
                            }
                        </c:forEach>
                    }},
                {field:'createUser',title:'创建人',width:150},
                {field:'createDate',title:'创建时间',width:150}
            ]],