问JQuery ajax调用默认超时值

EN

$.ajax({
    url: "/ajax_json_echo/",
    timeout: 500,
    error: function(jqXHR, textStatus, errorThrown) {
        alert(textStatus); // this will be "timeout"
    }
});

timeout
Type: Number
Set a timeout (in milliseconds) for the request. A value of 0 means there 
will be no timeout. This will override any global timeout set with 
$.ajaxSetup(). The  timeout period starts at the point the $.ajax call is made; 
if several other  requests are in progress and the browser has no connections 
available, it is  possible for a request to time out before it can be sent. In 
jQuery 1.4.x and  below, the XMLHttpRequest object will be in an invalid state if 
the request  times out; accessing any object members may throw an exception. In 
Firefox 3.0+  only, script and JSONP requests cannot be cancelled by a timeout; 
the script  will  run even if it arrives after the timeout period.