Extjs显示从数据库取出时间转换JSON后的出现问题

var record = Ext.data.Record.create([
{ name: 'PublicDate', mapping: 'PublicDate', dateFormat: 'Y-m-d', convert: function (v) {
if (v == null) {
return null;
}
var d = new Date();
var str = v.toString();
var str1 = str.replace("/Date(", "");
var str2 = str1.replace(")/", "");
var dd = parseInt(str2);
d.setTime(dd);
return d;
} }
]);

var cm = new Ext.grid.ColumnModel([
{ header: '发布时间', dataIndex: 'PublicDate', width: 120, align: 'center', renderer: Ext.util.Format.dateRenderer('Y-m-d') }
]);