XHR状态的JQuery Ajax错误为0; 意思是没有连接

我有以下代码片段

$.ajax({ method : "GET", url : 'http://projectstorehouse.com/travelnews/index.html', data : "", success : function(){ alert("Hello"); }, error : function(jqXHR, status, error){ if (jqXHR.status === 0) { alert('Not connected.\nPlease verify your network connection.'); } else if (jqXHR.status == 404) { alert ('The requested page not found. [404]'); } else if (jqXHR.status == 500) { alert ('Internal Server Error [500].'); } else if (exception === 'parsererror') { alert ('Requested JSON parse failed.'); } else if (exception === 'timeout') { alert ('Time out error.'); } else if (exception === 'abort') { alert ('Ajax request aborted.'); } else { alert ('Uncaught Error.\n' + jqXHR.responseText); } } }); 

并且无法弄清楚与之相关的问题; 显示的消息是jqXHR.status == 0。 可以访问urlhttp://projectstorehouse.com/travelnews/index.html

谁能告诉我哪里错了;