extjs分页全显了，不能出现分页，不用后台，我想模拟出来那些分页的效果

function GridBasic() {
//1. 定义表格
var cm = new Ext.grid.ColumnModel([
{ header: '编号', dataIndex: 'id',sortable:true},
{ header: '性别', dataIndex: 'sex',sortable:true},
{ header: '名称', dataIndex: 'name',width:'20',sortable:true},
{ header: '描述', dataIndex: 'desciption',width:'10',sortable:true}
]);


//2. 创建数据源
var data = [
['1','男','张三丰','是个作家'],
['2','男','石曼迪','会武功'],
['3','男','姜子牙','能捉鬼'],
['4','女','穆桂英','好像是皇帝'],
['5','男','孙悟空','高级程序员'],
['6','男','张三丰','是个作家'],
['7','男','石曼迪','会武功'],
['8','男','姜子牙','能捉鬼'],
['9','女','穆桂英','好像是皇帝'],
['10','男','孙悟空','高级程序员']
];
var ds = new Ext.data.Store({
proxy: new Ext.data.MemoryProxy(data),
reader: new Ext.data.ArrayReader({}, [
{ name: 'id' },{ name: 'sex' },{ name: 'name' },{ name: 'desciption' }
])
});



var grid = new Ext.grid.GridPanel({
el:'grid',
ds: ds,
cm: cm,
width: 500,
height: 260,
viewConfig: {
forceFit: true
},
bbar:new Ext.PagingToolbar({
pageSize:5,
store:ds,
displayInfo: true,
displayMsg: '显示第{0}条到{1}条记录，一共{2}条数据',
emptyMsg: "没有记录"
})
});
grid.render();
ds.load();


}
Ext.onReady(GridBasic); //
</script>