jQuery Grid Plugin - jqGrid

hiiii...

i'm a newbie..

i have a grid that code like that

jQuery('#tableGrid').jqGrid({
    scroll: 1,
       //url:'../admspanel/maingridrptsentmail.php',
    datatype: "xml",
    height: 470,
    mtype:"POST",
       colNames:['No','Mail', 'Count'],
       colModel:[
           {name:'no',index:'no', width:25, align:"right"},
           {name:'Mail',index:'Mail', width:515},
           {name:'countMail',index:'countMail', width:100, align:"right",formatter:'integer',formatoptions:{thousandsSeparator:","}},
       ],
       rowNum:100,
       //rowList:[10,20,30],
       pager: '#navGrid',
       sortname: 'Mail',
    viewrecords: true,
    sortorder: "asc",
    multiselect: false,
    subGrid : true,    
    reloadGrid:false,
    //subGridUrl: '../admspanel/subgridrptsentmail.php',
    subGridModel: [{ name  : ['No','Sent Date','Type','Subject','Mail'],
                    width : [25,100,100,200,300],
                    align : ['right'] }
    ],
    caption: "Examplel",
    footerrow: true,
    userDataOnFooter: true
});
jQuery('#tableGrid').jqGrid('navGrid','#navGrid',{add:false,edit:false,del:false,search:false,refresh:false});

i try to get name and width of colModel

my code to get col model like that

var a = $("#tableGrid").jqGrid('getGridParam','colModel');
alert(a);

it return [object object], [object object], [object object], [object object]

how can i get that name and width of colmodel?

is my code wrong ?

correct me if i have wrong..

what should i do to complete it?

can some body help me?

Thanks