node.js - 在本地主机上运行时，Firebase 出现 CORS 错误

Question

运行项目时出现以下错误。

Failed to load https://us-centralx-xxx.cloudfunctions.net/xxx: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:3000' is therefore not allowed access. The response had HTTP status code 500.

阅读了很多SO帖子后，我找到了以下解决方案，我需要添加 Access-Control-Allow-Origin 、 Access-Control-Allow-Methods 和 Access-Control-Allow-Headers

const HEADERS = {
    'Accept': 'application/json',
    'Content-Type': 'application/json',
    'Access-Control-Allow-Origin':  'http://localhost:3000/',
    'Access-Control-Allow-Methods': 'POST',
    'Access-Control-Allow-Headers': 'X-Requested-With,content-type'
};

但是，错误仍然存​​在。我该如何解决这个问题？

更新

exports.uploadFile = functions.https.onRequest((req, res) => {
        res.setHeader("Access-Control-Allow-Origin", "*");

        res.setHeader('Access-Control-Allow-Methods', 'GET,POST,DELETE,HEAD,PUT,OPTIONS');
        res.setHeader('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');


    res.status(200).json({
        message: req.body
    });
});

Answer 1

在 Node.js 服务器中设置适当的 header 以允许受控的 CORS 请求:

app.use((req, res, next) => {
  const origin = req.headers.origin;
  // arrayOfValidOrigins is an array of all the URL from where you want to allow 
  // to accept requests. In your case: ['http://localhost:3000'].
  // In case you want to accept requests from everywhere, set:
  // res.setHeader('Access-Control-Allow-Origin', '*');
  if (arrayOfValidOrigins.includes(origin)) {
    res.setHeader('Access-Control-Allow-Origin', origin);
  }

  // Here allow all the HTTP methods you want
  res.header('Access-Control-Allow-Methods', 'GET,POST,DELETE,HEAD,PUT,OPTIONS');
  // Here you allow the headers for the HTTP requests to your server
  res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
  // Method to reference to the next Node.js function in your flow
  next();
});

您的另一个选择是使用 Express.js CORS package并根据您的需要进行配置。