Test Case:
Code:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
    <title></title>
    <link rel="stylesheet" type="text/css" href="Extjs/resources/css/ext-all.css"/>    
    <script type="text/javascript" src="Extjs/bootstrap.js"></script>
</head>
<body>    
    <script type="text/javascript">

        Ext.onReady(function(){
            if(Ext.BLANK_IMAGE_URL.substr(0,4)!="data"){                
                Ext.BLANK_IMAGE_URL="./images/s.gif";
            }
            
            Ext.create("Ext.panel.Panel",{
                title:"",
                width:400,
                height:400,
                renderTo:Ext.getBody(),
                bodyStyle:"background:#DFE9F6",
                layout:"hbox",
                defaults:{xtype:"form",bodyPadding:5,
                    bodyStyle:"background:#DFE9F6",flex:1,height:350,
                    url:"Validation.asp",
                    defaultType:"textfield",
                    fieldDefaults:{labelWidth:80,                        
                        labelSeparator:":",anchor:"0"
                    },                    
                    bbar:[
                        {text:"Save",handler:function(){
                            var f=this.up("form").getForm();
                            if(f.isValid())
                                f.submit({
                                    waitMsg: "Save……",
                                    waitTitle: "Save",
                                });
                        }}
                    ]
                },
                items:[
                    {title:"JSON",
                        items:[
                            {fieldLabel:"field1",name:"field1"},
                            {fieldLabel:"field2",name:"field2",msgTarget:"side"},
                            {fieldLabel:"field3",name:"field3",msgTarget:"title"},
                            {fieldLabel:"field4",name:"field4",msgTarget:"under"},
                            {fieldLabel:"field5",name:"field5",msgTarget:"label1"},
                            {xtype:"label",id:"label1"}
                    ]}
                ]
            })
            
        });
    </script>
</body>
</html>
Validation.asp
Code:
<%
Response.Charset="utf-8"
Response.ContentType="text/javascript"

%>
{
  "success": false,
  "errors": {
    "field1": "requires"
  }
}
Click save button,result:
1.PNG