ajax在跨域get的时候会出现如标题所示的error get本地文件就不会 见如下代码

//get 本地
$.ajax({
            url:"http://localhost/tickets/json/api_airport.json",type:'GET',dataType:"json",success:function(data){console.log(data.results.result[1].category);}
        });

//跨域get
$.ajax({
            url:"http://api.master18.tiket.com/search/autocomplete/hotel?q=mah&token=90d2fad44172390b11527557e6250e50&secretkey=83e2f0484edbd2ad6fc9888c1e30ea44&output=json",crossDomain:true,beforeSend: function(x) {
                if(x && x.overrideMimeType) {
                    x.overrideMimeType("application/j-son;charset=UTF-8");
                }
            },success:function(data){console.log("Success");}
        });

<?PHP
// File Name: proxy.PHP
if (!isset($_GET['url'])) die();
$url = urldecode($_GET['url']);
$url = 'http://' . str_replace('http://','',$url); // Avoid accessing the file system
echo file_get_contents($url);

ajax改为：

$.ajax({
    url:"proxy.PHP",data: "url=http%3A%2F%2Fapi.master18.tiket.com%2Fsearch%2Fautocomplete%2Fhotel%3Fq%3Dmah%26token%3D90d2fad44172390b11527557e6250e50%          26secretkey%3D83e2f0	484edbd2ad6fc9888c1e30ea44%26output%3Djson",success:function(data){console.log(data.results.result[1].category);}
});

And the reason:

You're getting this error because of XMLHttpRequest same origin policy,which basically boils down to a restriction of ajax requests to URLs with a different port,domain or protocol. This restriction is in place to prevent cross-site scripting (XSS) attacks.