jQuery EasyUI中DataGird动态生成列的方法

<table id="dg"></table>
<script>
function easyUIDataGrid(medid) {
var $datagrid = {};
var columns = new Array();
$datagrid.title = "";
$datagrid.height = $(window).height() - 31;
$datagrid.width = $(window).width();
$datagrid.sortName = "dt";
$datagrid.sortOrder = "desc";
$datagrid.idField = "id";
var param = { "medid": medid };
$.ajax({
url: 'getCol.page',
type: 'post',
data: "medid=" + medid,
dataType: "json",
async: false,
success: function (returnValue) {
　　　　　　　　　　　　//异步获取要动态生成的列 别名，宽度也可以
var arr = returnValue;
$.each(arr, function (i, item) {
columns.push({ "field": item.colname, "title": item.colalias, "width": 100, "sortable": true });
});
$datagrid.columns = new Array(columns);
$('#dg').datagrid($datagrid);
}
});
}
</script>