我先描述我遇到的情况：
nodejs后端，设置：
app.all('*', function(req, res, next) {
console.log("appuse");
res.header("Access-Control-Allow-Origin","*");
res.header("Access-Control-Allow-Headers","Origin, Accept-Language, Accept-Encoding,X-Forwarded-For, Connection, Accept, User-Agent, Host, Referer, Cookie, Content-Type, Cache-Control,*");
res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
res.header("Access-Control-Allow-Credentials",true);
res.header("X-Powered-By",' 3.2.1');
res.header("Content-Type", "application/json;charset=utf-8");
next();
});然后前端ajax请求后端，后端会返回set-cookie
set-cookie:connect.sid=s%3ACOrynUfg9BleXlivy2GWX2n6gYzSnHoP.lX51TZD1YazMhcDJFTdqwPjN6pL7q1dcAhCEElVRGxQ; Path=/; Expires=Sun, 30 Oct 2016 16:15:03 GMT; HttpOnly
像上面那样
![[웹 프런트엔드] Node.js 빠른 시작](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
服务器如果要发送Cookie，Access-Control-Allow-Origin就不能设为星号，必须指定明确的、与请求网页一致的域名。同时，Cookie依然遵循同源政策，只有用服务器域名设置的Cookie才会上传，其他域名的Cookie并不会上传，且（跨源）原网页代码中的document.cookie也无法读取服务器域名下的Cookie。