easyui treegrid根据条件定义行样式

$('#tt').treegrid({
// url:'get_data.php',
data: data,
title:"Folder Browser" ,
idField:'id',
treeField:'name',
rowStyler: function(row)
{if (row.size=='')
{
return 'background-color:#6293BB;color:#fff;font-weight:bold;';
}
},
columns:[[
{title:'name',field:'name',width:220},
{field:'size',title:'Persons',width:100,align:'right'},
{field:'date',title:'Begin Date',width:120}
]],
onLoadSuccess: function(row){$(this).treegrid('enableDnd', row?row.id:null);},
onDblClickCell:function(){$('#tt').treegrid('getEditor',{index:row.id,field:'name'}).target.val(formula_text);}

});