Javascript跨域

 1 function createCORSRequest(method, url) { 
 2    var xhr = new XMLHttpRequest();   
 3    if ("withCredentials" in xhr) {  
 4       xhr.open(method, url, true);    
 5    } else if (typeof XDomainRequest!= "undefined") {     
 6       xhr = new XDomainRequest();    
 7       xhr.open(method, url);      
 8    } else {        
 9      // 否则，浏览器不支持CORS      
10      xhr = null;      
11    }   
12    return xhr;
13 }