http.createServer((req,res)=>{
    //設置允許跨域的域名，*代表允許任意域名跨域
    res.setHeader("Access-Control-Allow-Origin","*");
    //跨域允許的header類型
    res.setHeader("Access-Control-Allow-Headers","Content-type,Content-Length,Authorization,Accept,X-Requested-Width");
    //跨域允許的請求方式
    res.setHeader("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
    
 
//設置響應頭信息
    res.setHeader("X-Powered-By",‘ 3.2.1‘)
    //讓options請求快速返回
    if(req.method == "OPTIONS"){return res.end();}
    }
}).listen(3000);

node 跨域請求設置