NodeJs 设置跨域后页面全部变成了源码在浏览器上显示

百度搜索跨域后得到

app.all('*', function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "X-Requested-With");
  res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
  res.header("X-Powered-By",' 3.2.1')
  res.header("Content-Type", "application/json;charset=utf-8");
  next();
});

虽然 我初学目前看不懂写的什么，但是经过测试就是这个跨域设置，导致接收的html文件被pre标签包裹。

app.all('*', function(req, res, next) {
  res.header("Access-Control-Allow-Credentials","true");
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Methods","PUT,GET,POST,DELETE,OPTIONS");
  res.header("ACCess-Control-Allow-Headers","Content-Type,username");
  next();
});

更改，再次读取页面，成功返回html。