跨域只请求了一次204

Question

用的nestjs nest的内部用的是express
如果直接在header中设置

app.use((req, res, next) => {

res.header("Access-Control-Allow-Origin", "*");
res.header('Access-Control-Allow-Methods', 'OPTIONS,GET,POST,PUT,DELETE');
res.header("Access-Control-Allow-Headers", "Origin,X-Requested-With,Content-Type,Accept,Authorization");
res.header("cache-control", "no-cache");
res.header("content-type", "application/json; charset=utf-8");
res.header("ETag", '');
if ('OPTIONS' === req.method) {
  res.send(204);
}
else {
  next();
}

});
但是浏览器只请求一次（204）就不再请求### 问题描述