w2ui-how to get sortData array in grid to apply for sorting?

There was an issue for me. In w2ui grid I used to access the remote data through the grid url. And I use server language node.js. If I use a local data automatically performs a sort of grid, but I use romote data. i looked to find w2ui website. if i use remote data, i need to use a .sortData array to sort. But I can not get sortData array. Please advise.

my code

 $('#vidgetGrid').w2grid({
                        name : 'vidgetGrid',
                        msgRefresh : 'DATA LOADING..',
                        fixedBody : true,
                        url : '/getDashVidgetList',
                        limit : 10,
                        offset : 0,
                        autoLoad : false,
                        show : {
                            toolbar : true,
                            toolbarSearch : true,
                            selectColumn : true,
                            footer : true
                        },
                        searches : [ {
                            field : 'name',
                            caption : 'NAME',
                            type : 'text'
                        } ],
                        columns : [
                        {
                            field : 'category',
                            caption : 'CATEGORY',
                            size : '30%',
                            resizable : true,
                            sortable : true
                        }, {
                            field : 'name',
                            caption : 'NAME',
                            size : '30%',
                            resizable : true,
                            sortable : true
                        }, {
                            field : 'type',
                            caption : 'TYPE',
                            size : '30%',
                            resizable : true,
                            sortable : true
                        }, {
                            field : 'user',
                            caption : 'WRITER',
                            size : '40%',
                            resizable : true,
                            sortable : true
                        }, {
                            field : 'share',
                            caption : 'SHARE',
                            size : '120px',
                            resizable : true,
                            sortable : true
                        }, {
                            field : 'createtime',
                            caption : 'CREATETIME',
                            size : '120px',
                            resizable : true,
                            sortable : true
                        }, {
                            field : 'status',
                            caption : 'STATUS',
                            size : '120px',
                            resizable : true,
                            sortable : true
                        } ],
                        postData : {
                           Name : searchText
                        },
                        sortData:[
                        {field:"name",direction:"desc"},{field:"category",direction:"asc"},{field:"status",direction:"asc"}
                         ]
     });

my node.js

    exports.getDashVidgetList=function(req,res){
       var sort=req.param("sortData");
       console.log(sort)--->undefined
    }