my easyui version 1.3.4 and my jquery version is 1.9.1

The 'success' is called after the response has been returned from server, no matter what the result is. Due to the network issues, you may get the timeout information from 'success' function. So you need to detect if the data is what you expect.

In my test, success not called!In my tomcat server, I create a html page with javascript below, and then visit the page. When submit form, 'success' is called. but when I stop tomcat, and submit the form, 'success' never called!
The code:
$(function(){
   $("#frm").form({
                url: "http://localhost:3292/test/test.htm",
                success: function (data) {
                    alert("success");
                }
            });   
});

I have read this post:
http://www.jeasyui.com/forum/index.php?topic=8.msg17#msg17

but if action url can't reach, there is no success event.
my code:
$("#frm").form(
    {
       url:'...',
       onSubmit:function(){
           $.messager.progress();
           return true;
       },
       success:function(data){
           $.message.progress('close');
           ...
       }
    }
)

So if success event can't fire, progress will alway shown and user can't do anything.
In my environment, some computer's network is poor, so I often meet success event can't fire