CORS问题:所请求的资源上不存在"Access-Control-Allow-Origin"标头

问题描述

var enableCORS = function(req, res, next) {
res.header('Access-Control-Allow-Origin', '*');
res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization, Content-Length, X-Requested-With');

// intercept OPTIONS method
if ('OPTIONS' == req.method) {
  res.send(200);
}
else {
  next();
}
};
app.use(enableCORS);

我发现要在服务器端使用以下代码段，但是当我尝试进行POST时，仍然收到错误消息:所请求的资源上没有'Access-Control-Allow-Origin'标头.

I found out to use the following snippet in the server side, but still when i try to POST I am getting the error No 'Access-Control-Allow-Origin' header is present on the requested resource.

推荐答案

我仅使用以下行:

res.header("Access-Control-Allow-Origin", "*");

它有效.您有没有在发送标题之前打印任何其他内容的机会?标头必须先发送.中间件代码应优先于其他任何东西.

And it works. Any chance you print anything else before sending the headers? headers must be sent before anything else. The middleware code should be prior to anything else.

您确定代码正在执行吗?执行一些"console.log"打印以确保正在调用enableCORS.

Are you sure the code is getting executed? do some 'console.log' prints to make sure the enableCORS is being called.

最后，使用chrome开发人员工具(或任何等效工具)查看从服务器返回的标头.对于chrome，请转到网络=>有问题的请求=>标头=>响应标头，并确保CORS标头在其中.

Lastly, use chrome developer tools (or any equivalent tool) to view the headers returned from the server. For chrome, go to network => the problematic request => headers => Response headers, and make sure the CORS headers are there.

更新尝试使用以下内容(摘自此处):

UpdateTry using the following (taken from here):

res.header('Access-Control-Allow-Origin', '*');
res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE'); # OPTIONS removed
res.header('Access-Control-Allow-Headers', 'Content-Type');

这篇关于CORS问题:所请求的资源上不存在"Access-Control-Allow-Origin"标头的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！