The code posted before only demonstrates how to define a 'sorter'. Here is the example shows how to custom sorting on a number column.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>jQuery EasyUI Demo</title>
<link rel="stylesheet" type="text/css" href="https://www.jeasyui.com/easyui/themes/default/easyui.css">
<link rel="stylesheet" type="text/css" href="https://www.jeasyui.com/easyui/themes/icon.css">
<script type="text/javascript" src="https://www.jeasyui.com/easyui/jquery.min.js"></script>
<script type="text/javascript" src="https://www.jeasyui.com/easyui/jquery.easyui.min.js"></script>
<script>
var data = [
{"no":"1", "productid": "FI-SW-01", "productname": "Koi", "unitcost": "10.00", "status": "P", "listprice": "36.50", "attr1": "Large", "itemid": "EST-1" },
{"no":"3", "productid": "RP-LI-02", "productname": "Iguana", "unitcost": "12.00", "status": "P", "listprice": "35.50", "attr1": "Green Adult", "itemid": "EST-13" },
{"no":"4", "productid": "FL-DSH-01", "productname": "Manx", "unitcost": "12.00", "status": "P", "listprice": "158.50", "attr1": "Tailless", "itemid": "EST-14" },
{"no":"10", "productid": "K9-DL-01", "productname": "Dalmation", "unitcost": "12.00", "status": "P", "listprice": "18.50", "attr1": "Spotted Adult Female", "itemid": "EST-10" },
{"no":"11", "productid": "RP-SN-01", "productname": "Rattlesnake", "unitcost": "12.00", "status": "P", "listprice": "38.50", "attr1": "Venomless", "itemid": "EST-11" },
{"no":"2", "productid": "RP-SN-01", "productname": "Rattlesnake", "unitcost": "12.00", "status": "P", "listprice": "26.50", "attr1": "Rattleless", "itemid": "EST-12" },
{"no":"5", "productid": "FL-DSH-01", "productname": "Manx", "unitcost": "12.00", "status": "P", "listprice": "83.50", "attr1": "With tail", "itemid": "EST-15" },
{"no":"6", "productid": "FL-DLH-02", "productname": "Persian", "unitcost": "12.00", "status": "P", "listprice": "23.50", "attr1": "Adult Female", "itemid": "EST-16" },
{"no":"7", "productid": "FL-DLH-02", "productname": "Persian", "unitcost": "12.00", "status": "P", "listprice": "89.50", "attr1": "Adult Male", "itemid": "EST-17" },
{"no":"8", "productid": "AV-CB-01", "productname": "Amazon Parrot", "unitcost": "92.00", "status": "P", "listprice": "63.50", "attr1": "Adult Male", "itemid": "EST-18" }
]
function mysorter(a,b){
return parseInt(a)>parseInt(b)?1:-1;
}
</script>
</head>
<body>
<table class="easyui-datagrid" title="Basic DataGrid" style="width:700px;height:250px"
data-options="singleSelect:true,remoteSort:false,fitColumns:true,data:data">
<thead>
<tr>
<th data-options="field:'no',width:50,align:'center',sortable:true,sorter:mysorter">No</th>
<th data-options="field:'itemid',width:80">Item ID</th>
<th data-options="field:'productid',width:100">Product</th>
<th data-options="field:'listprice',width:80,align:'right'">List Price</th>
<th data-options="field:'unitcost',width:80,align:'right'">Unit Cost</th>
<th data-options="field:'attr1',width:250">Attribute</th>
<th data-options="field:'status',width:60,align:'center'">Status</th>
</tr>
</thead>
</table>
</body>
</html>