JQuery EasyUI treegrid 在子結點前加復選框

$(function(){  
   $("#treeTaocan2").treegrid({ 
    idField:'id',  
    treeField:'text',  
    nowrap: false, 
    rownumbers: true,
    checkbox: true,
    lines: false, 
    dnd: true,
    onlyLeafCheck: true,
    animate: true,
    collapsible: true, 
    singleSelect: true, 
    columns:[[  
        {title:'text',field:'text',width:180,formatter:function(value,rowData,rowIndex){
            if(rowData.id!= "root" && rowData.id.indexOf("zu_")==-1)
            {   //text 名稱前面加復選框
                return "<input type='checkbox' id='taocan_"+rowData.id+"' "+(rowData.checked?'checked':'')+"/>" + rowData.text;
            }else{
                return rowData.text;
            }
        }},
        {title:'price','field':'price',width:180},
        {title:'price1','field':'price1',width:180}
    ]]  
});
$("#treeTaocan2").treegrid("loadData",data)  
//去掉結點前面的文件及文件夾小圖標
$(".tree-icon,.tree-file").removeClass("tree-icon tree-file");
$(".tree-icon,.tree-folder").removeClass("tree-icon tree-folder tree-folder-open tree-folder-closed"); 
});
//獲取選中的結點
function getSelected(){ 
    var idList = "";  
     $("input:checked").each(function(){
        var id = $(this).attr("id"); 
        if(id.indexOf("taocan_")>-1)
            idList += id.replace("taocan_",'')+',';
     })
    alert(idList);
}